Use of the Advanced Photon Source and Center for Nanoscale Materials, Office of Science User Facilities operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. We acknowledge Dr. Han Wen, NHLBI / National Institutes of Health, Bethesda, MD 20892, USA, for many helpful suggestions during the data processing.

1. Planning of the Experiment
<ol>
	<li>Identify the synchrotron beamline. Contact beamline scientist to find the appropriateness of the experiment at that beamline. 
	NOTE: Experiments reported in this manuscript were performed at the 1-BM-B beamline, which is dedicated to optics and detectors testing, under XSD of APS.</li>
	<li>Submit a user proposal and beam time request.</li>
	<li>Work out the details of the experiment with the beamline scientist and specify the required instruments including motorized stages for the grating and detector alignment, 2-dimensional detector (CCD or CMOS), long translation stage covering the least and farthest distances needed between the detector and the phase grating.</li>
	<li>Prepare for the beam time by following the instructions provided in the relevant website. Complete the safety trainings and necessary experimental safety assessment form.</li>
</ol>
2. Preparation of the 2-D Checkerboard Phase Grating
<ol>
	<li>Determine the period of the grating, p, which is related to the period of the interferogram pattern, p&#952;, along different transverse direction angle &#952;. The visibility values, V&#952;(d), of the interferogram along different &#952; angle oscillate as a function of the grating-to-detector distance, d. 
	For a 2-D checkerboard &#960;/2 phase grating, V&#952;(d) peaks at distances, 
	<img alt="Equation 1" src="/files/ftp_upload/53025/53025eq1.jpg" /> 
	with n = 1, 2, 3&#8230; and &#955; the photon wavelength. The interferogram pattern has a characteristic period of p&#952; = p/&#8730;2 along the diagonal direction of the square blocks and a period of p&#952; = p/2 along the edge of the square blocks. The choice of p thus relies on the following criteria.</li>
	<li>Make sure at least several V&#952;(d) peaks are within the largest grating-to-detector distance, or the space limit of the experimental station, dmax. To satisfy dn,&#952; &#60; dmax, it follows 
	<img alt="Equation 2" src="/files/ftp_upload/53025/53025eq2.jpg" /> 
	For n = 5, dmax = 1 m, &#955; = 0.06888 nm (18 keV), it gives p&#952; &#60; 3.9 &#181;m.</li>
	<li>Within dmax, make sure that the height of the V&#952;(d) peak at the largest distance dn,&#952; is less than a factor &#947; of that of the first V&#952;(d) peak at d1,&#952; in order to have an accurate Gaussian decay function fitting. Hence, &#947; = V&#952;,n(d) / V&#952;,1(d) which is the ratio of the nth peak visibility to the first peak. For an X-ray source following Gaussian intensity distribution with the coherence length, &#958;&#952;, the period of a &#960;/2 phase grating needs to satisfy 
	<img alt="Equation 3" src="/files/ftp_upload/53025/53025eq3.jpg" /> 
	for instance, with &#947; = 10%, &#958;&#952; = 5 &#181;m and parameters above, it gives p&#952; &#62; 2.4 &#181;m.</li>
	<li>Ensure that the period of the interferogram pattern, p&#952;, is a few times larger than the spatial resolution of the detector by choosing the correct detector systems.</li>
	<li>Determine the thickness, T, of the grating required for a phase shift of, &#966;, at the X-ray photon wavelength, &#955;, using 
	<img alt="Equation 4" src="/files/ftp_upload/53025/53025eq4.jpg" /> 
	where &#948; is the refractive index decrement of the phase shifting material. For example, the refractive index decrement for Au is 9.7&#215;10-6 for 18 keV. The Au thickness for &#966; = &#960;/2 phase grating is thus 1.8 &#181;m.</li>
	<li>Fabricate the phase grating by electroplating Au into a patterned polymer mold on a silicon nitride (Si3N4) window. 
	NOTE: The procedure for preparation of silicon nitride (Si3N4) window substrate and fabrication of the grating structure are presented below.
	<ol>
		<li>Prepare the substrate by first releasing the Si3N4 membrane to form the X-ray transparent window.</li>
		<li>Acquire silicon (Si) wafers with low stress (&#60;250 MPa) Si3N4 deposited on both sides of the wafer from a vendor.</li>
		<li>Load the wafer into a magnetron sputtering deposition system to deposit Cr and Au to act as an electroplating base.</li>
		<li>Deposit 5 nm of Cr then 30 nm of Au on one side of the wafer, following manufacturer&#39;s directions. 
		NOTE: The deposition processes from the system manufacturer will include information such as deposition rate.</li>
		<li>Unload wafer from deposition tool. Use the side of the wafer deposited with Cr and Au for grating fabrication.</li>
		<li>Determine the total size of the grating and then design a photolithography mask to pattern membranes slightly larger. Use the design to acquire a photolithography mask by purchasing from a vendor or fabricate the photolithography mask.</li>
		<li>Spin a 3-&#181;m thick layer of photoresist on the back side of the wafer where there is no Cr and Au coating. Expose the resist with a UV lithography tool for 20 sec using the designed photolithography mask. Develop the exposed resist in aqueous alkaline developer solution for 30 sec then rinse with deionized water and dry with flowing N2.</li>
		<li>Load the wafer into a reactive ion etching (RIE) tool with patterned photoresist facing the chamber. Use CF4 plasma to etch the exposed Si3N4 following tool instructions.</li>
		<li>Evacuate the etching chamber and input etch recipe into RIE tool. Run the recipe until the Si3N4 layer is etched completely and the Si layer is exposed in the pattern.</li>
		<li>Etch the exposed Si on the wafer backside by submerging into 30% KOH solution heated to 80 &#176;C for about 8 hr. Etch rate is approximately 75 &#181;m/hr using the stated recipe.</li>
		<li>After Si etch is finished, rinse with deionized water and dry with flowing N2. The sample is ready for grating fabrication.</li>
	</ol>
	</li>
	<li>Fabricate the electroplating mold for the phase grating using the following steps.
	<ol>
		<li>Design the square checkerboard grating pattern and compensate for pattern biasing by reducing the exposed square pattern size by 100-250 nm. Include a &#62;50-&#181;m wide frame around the grating pattern for thickness confirmation later in the process.</li>
		<li>Load the sample into a resist spin coater and deposit poly (methyl methacrylate) (PMMA) positive resist solution on the grating side of the sample. Run the resist spin coater to form a 2 to 3.5-&#181;m thick resist film depending on desired final grating thickness. 
		NOTE: Spin curves with information on spin speed versus film thickness are provided by the PMMA solution vendor or can be determined empirically.</li>
		<li>Load the wafer into a 100 keV electron beam lithography system.</li>
		<li>Calibrate tool for exposure with a large exposure current greater than 10 nA.</li>
		<li>Expose the PMMA resist using a 100 keV e-beam lithography tool to create the grating pattern, where areas exposed will be removed in the development step. Use an exposure dose range of 1,100-1,250 &#181;C/cm2 depending on resist thickness.</li>
		<li>Unload the sample from the tool.</li>
		<li>Develop the exposed resist by submerging in a 7:3 (by volume) isopropyl alcohol (IPA): deionized water solution for 30-40 sec with gentle swirling. Rinse with IPA, and then dry with flowing N2. Ensure the PMMA was fully developed by looking at exposed area with an optical microscope.</li>
		<li>Load the sample into a RIE tool with PMMA pattern facing the chamber.</li>
		<li>Evacuate the etching chamber and input descum etch recipe into RIE tool. The descum process is a short (&#60;30 sec) O2 plasma based etch to remove any residual PMMA from the exposed grating area.</li>
	</ol>
	</li>
	<li>Finish the Au grating by electroplating into the fabricated mold using the following steps.
	<ol>
		<li>Make sure the electroplating mold thickness by scanning the probe of a profilometer across the frame included for thickness confirmation.</li>
		<li>Submerge the sample into the Au-sulfite electroplating solution heated to 40 &#176;C. The electroplating setup is composed of a beaker filled with the electroplating solution, a constant current DC power supply, and a Pt mesh anode.</li>
		<li>Determine the plating area of the sample by calculating the exposed Au in the exposed pattern, then calculate current for the desired current density, which is the primary variable used to set the deposition rate.</li>
		<li>Calculate plating time to reach desired grating thickness using the plating rate determined by the applied current density.</li>
		<li>Turn on the DC power supply to apply the determined current on the sample, acting as a cathode, and plate for approximately half the total plating time.</li>
		<li>Measure the plating thickness using the same method used in step 2.8.1.</li>
		<li>Turn on the DC power supply to electroplate Au into the PMMA mold and electroplate to the desired grating thickness, taking into account the plated height measured in step 2.8.6.</li>
	</ol>
	</li>
	<li>Remove the polymer mold using a heated solvent by submerging the sample. Then inspect with an optical microscope and a scanning electron microscope (SEM) to confirm grating period, duty cycle, and grating thickness. 
	NOTE: Have two 2-D checkerboard phase gratings (one for the experiment and one as a spare) ready, a few days before the experiment begins.</li>
</ol>
3. Experiment Setup and Alignment at the Synchrotron Facility
<ol>
	<li>Request the beamline scientist to set the X-ray beam energy or wavelength to the desired value that matches the phase grating. Routinely used X-ray energies at the APS 1-BM beamline are between 6&#160;and 28&#160;keV. In this case, tune the photon energy to 18 keV.</li>
	<li>Select the desired objective lens for the detector system. Here, use a Coolsnap HQ2 CCD detector with 1,392 &#215; 1,040 imaging pixels of 6.45 &#215; 6.45 &#181;m2 pixel size. To resolve the smallest interference pattern, use an EC plan Neofluar 10&#215; objective. The effective pixel size of the detector system including the magnification effect of microscopic objective is thus 0.64 &#181;m. The estimated spatial resolution is about 2 &#181;m, which is mainly due to the point spread function of the detector system.</li>
	<li>To set the rough focusing of the detector system, place the scintillator (lutetium-yttrium oxyorthosilicate, 150-&#181;m thick) at the &#39;working distance&#39; from the lens (~5.2 mm for the used system). At first, set the focus under ambient light by monitoring the images acquired under &#39;continuous mode&#39; as the scintillator position is adjusted using a pico-motor.</li>
	<li>Move the 2-D detector into the X-ray beam, by using vertical and horizontal stages align the center of the detector to the beam center.</li>
	<li>Place a &#39;phase sample&#39;, for example a piece of Styrofoam, into the X-ray beam. Perform the fine focusing of the detector system by observing the scattering pattern from the phase sample and adjusting the scintillator position until the highest image sharpness.</li>
</ol>
4. Performing Coherence Measurements
<ol>
	<li>Place the 2-D checkerboard grating into the X-ray beam where the coherence of the beam is to be measured. In this case it is at 34 meters from the bending magnet source.</li>
	<li>Adjust the plane of the 2-D checkerboard phase grating to be perpendicular to the direction of the X-ray beam propagation.</li>
	<li>Center the grating to the X-ray beam by using the motorized stages and looking at the images acquired under detector continuous mode.</li>
	<li>Rotate the grating around the X-ray beam propagation direction (y) so that the diagonal direction of the checkerboard pattern is along the desired transverse beam direction. In this case, align the diagonal directions of the checkerboard (preferred measuring directions) in the horizontal and vertical directions of the beam. Fine tune the grating rotations around the other two axes (x and z) to ensure its perpendicularity to the X-ray beam, which is achieved by maximizing the interferogram periods in both the horizontal and vertical directions.</li>
	<li>Move the detector system as close as physically possible to the phase grating along the beam propagation direction. In this study, use a distance of 43 mm.</li>
	<li>Calculate the smallest period in the interference pattern. The &#960;/2 checkerboard grating with period p = 4.8 &#181;m will generate an interference pattern with p&#952; = 3.4 &#181;m and p&#952; = 2.4 &#181;m (smallest period) along the diagonal and the non-diagonal directions of the checkerboard pattern, respectively. Estimate the number of data points needed in-between V&#952;(d) peak positions given by Equation (1) to obtain a smooth curve.</li>
	<li>Select the appropriate exposure time for each interferogram, four seconds in this case.</li>
	<li>Record interferograms with the same exposure time (e.g., 4 sec) at different grating-to-detector distances. Choose the exposure time based on the beam intensity level. Starting from the minimum grating-to-detector distance (43 mm), move the detector downstream of the X-ray by small intervals (10 mm determined based on step 4.6) and record an interferogram at each detector position until the maximum possible grating-to-detector distance (750 mm).</li>
	<li>Acquire dark-frame images with the same exposure time (4 sec) but turn off the X-ray beam and keep all other experimental conditions the same.</li>
</ol>
5. Data Analysis
NOTE: There is currently no standard software available for the data analysis.
<ol>
	<li>Using the selected image processing program, read in the dark-frame image(s) and the data image. Correct the data image by subtracting the (averaged) dark-frame image.</li>
	<li>Fourier transform the dark-frame corrected image, which produces visible harmonic peaks in the horizontal (&#952; = 0&#186;), vertical (&#952; = 90&#186;) as well as &#952; = 45&#176; and &#952; = 135&#176; directions.</li>
	<li>Crop the 0th order harmonic image centered at the 0th order peak. The length and width of the image equal to the distances between the 0th and 1st order peaks along the horizontal and vertical directions, respectively. Similarly, obtain the 1st order harmonic images of the same length and width along the transverse direction of interest.</li>
	<li>Inverse Fourier Transform (IFT) the cropped harmonic images. Ratio of the mean of the amplitudes of the IFT image from the 1st order harmonic image along any transverse direction to that of the IFT image from the 0th order harmonic image gives the visibility along that direction. 
	Note that this process is valid if few high-frequency components exist in the measured interferogram. Otherwise, one can use the corresponding harmonic peak intensities of the Fourier transform images from step 5.4 instead. Due to the beam divergence, the harmonic peak positions will change gradually at different grating-to-detector distances. Therefore, a correction to p&#39;&#952; at each distance or a peak finding process is needed.</li>
	<li>Repeat step 5.1-5.4 for all the measured images at different grating-to-detector distances and save the visibility value of each image.</li>
	<li>Plot the visibility V&#952;(d) as a function of the grating-to-detector distance. Identify data points at V&#952;(d) peaks. Note that the full curve was measured just to better identify the peak positions given by Equation (1). Manually select peak data points as well as adjacent data points on either side of each peak.</li>
	<li>Draw Gaussian fitting function for the selected data points. Extract standard deviation, &#963;&#952;, of the Gaussian fitting function.</li>
	<li>Obtain the transverse coherence length, &#958;&#952;, using 
	<img alt="Equation 5" src="/files/ftp_upload/53025/53025eq5.jpg" /></li>
</ol>

<ol>
	<li>Als-Nielsen, J., McMorrow, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Elements of Modern X-ray Physics. , (2011).</li><li>Born, M., Wolf, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principle of Optics. , (1999).</li><li>Lin, J. J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+the+Spatial+Coherence+Function+of+Undulator+Radiation+using+a+Phase+Mask.">Measurement of the Spatial Coherence Function of Undulator Radiation using a Phase Mask.</a> Phys. Rev. Lett. 90 (7), 074801 (2003).</li><li>Cloetens, P., Guigay, J. P., De Martino, C., Baruchel, J., Schlenker, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fractional+Talbot+imaging+of+phase+gratings+with+hard+X-rays.">Fractional Talbot imaging of phase gratings with hard X-rays.</a> Opt. Lett. 22 (14), 1059-1061 (1997).</li><li>Guigay, J. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+partial+Talbot+effect+and+its+use+in+measuring+the+coherence+of+synchrotron+X-rays.">The partial Talbot effect and its use in measuring the coherence of synchrotron X-rays.</a> J. Synchrotron Rad. 11, 476-482 (2004).</li><li>Kluender, R., Masiello, F., Vaerenbergh, P. V., H&#228;rtwig, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+the+spatial+coherence+of+synchrotron+beams+using+the+Talbot+effect.">Measurement of the spatial coherence of synchrotron beams using the Talbot effect.</a> Phys. Status Solidi A. 206 (8), 1842-1845 (2009).</li><li>Pfeiffer, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shearing+Interferometer+for+Quantifying+the+Coherence+of+Hard+X-Ray+Beams.">Shearing Interferometer for Quantifying the Coherence of Hard X-Ray Beams.</a> Phys. Rev. Lett. 94 (1-4), 164801 (2005).</li><li>Marathe, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+transverse+coherence+of+x-ray+beam+with+2-D+phase+grating+interferometer.">Probing transverse coherence of x-ray beam with 2-D phase grating interferometer.</a> Opt. Express. 22 (12), 14041-14053 (2014).</li><li>Shi, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circular+grating+interferometer+for+mapping+transverse+coherence+area+of+X-ray+beams.">Circular grating interferometer for mapping transverse coherence area of X-ray beams.</a> Appl. Phys. Lett. 105 (1-6), 041116 (2014).</li><li>Zanette, I., David, C., Rutishauser, S., Weitkamp, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2D+grating+simulation+for+X-ray+phase-contrast+and+dark-field+imaging+with+a+Talbot+interferometer.">2D grating simulation for X-ray phase-contrast and dark-field imaging with a Talbot interferometer.</a> , 73-79 (2010).</li></ol>

The authors have nothing to disclose.

Figure 5 shows the estimated transverse coherence length along all four directions. Clearly, the 90&#176; direction has higher &#958;&#952; compared to 0&#176; direction. Since the beamline optics has negligible effect on the beam coherence at the grating relative location, the measured coherence area is inversely proportional to the source size area. The presented X-ray beam coherence measurement technique maps this accurately which can be shown as an ellipse with its major axis alon...

The third-generation hard X-ray synchrotron radiation sources, such as the APS at ANL, Lemont, IL, USA (http://www.aps.anl.gov), have had tremendous impacts on the development of X-ray sciences. A synchrotron radiation source generates a spectrum of electromagnetic radiations, from infrared to X-ray wavelengths, when charged particles, such as electrons, are made to move near the speed of light in a circular orbit. These sources have very unique properties such as high brightness, pulsed and pico-second timing structure, and large spatial and temporal coherence. X-ray beam spatial coherence is an important parameter of the third and fourth generation synchrotron sources and the number of experiments making use of this property has dramatically increased over the past two decades1. The future upgrades of these sources, such as the planned Multi-bend achromat (MBA) lattice for the APS storage ring, will dramatically increase the beam coherent flux (http://www.aps.anl.gov/Upgrade/). The X-ray beam can be tuned using a crystal monochromator to achieve higher temporal coherence. The transverse coherence of synchrotron sources is significantly higher than that of laboratory based X-ray sources because of the low electron-beam emittance and long propagation distance from the source to the experimental station.
Normally, Young&#39;s double-pinhole or double-slit experiment is used to measure the spatial coherence of the beam through the inspection of the visibility of the interference fringes2. To obtain the complete Complex Coherence Function (CCF), systematic measurements are needed with the two slits placed at different positions with various separations, which is, especially for hard X-rays, cumbersome and impractical. Uniformly Redundant Array (URA) can also be used for beam coherence measurement by employing it as a phase shifting mask3. Although the technique can provide the full CCF, it is not model-free. More recently, interferometric techniques based on Talbot effect were developed using the self-imaging property of periodic objects. These interferometers make use of the interferogram visibility measured at a few self-imaging distances downstream of the grating for obtaining the beam transverse coherence4-9. Measurements of transverse coherence using two grating system is also reported7.
Mapping the transverse beam coherence, simultaneously along vertical and horizontal directions was first reported by J. P. Guigay et al.5. Recently, scientists in the Optics Group, X-ray Science Division (XSD), of APS have reported two new techniques to measure beam transverses coherence along more than two directions simultaneously using two methods: one with a checkerboard phase grating8, and the other with a circular phase grating9.
In this paper the measurement and data analysis procedures are described for obtaining the transverse coherence of the beam along the 0&#176;, 45&#176;, 90&#176;, and 135&#176; directions relative to the horizontal direction, simultaneously. The measurements were carried out at the 1-BM beamline of APS with a checkerboard &#960;/2 phase grating. The details of this technique listed in the protocol sections include: 1) planning of the experiment; 2) preparation of the 2-d checkerboard phase grating; 3) experiment setup and alignment at the synchrotron facility; 4) performing coherence measurements; 5) data analysis. In addition, the representative results are shown to illustrate the technique. These procedures can be carried out at many synchrotron beamlines with minimum changes on the grating design.

<table border="0" cellpadding="0" cellspacing="0" width="628">
	<tbody>
		<tr height="63">
			<td height="63" style="height:63px;width:215px;">1-BM-B bending magnet x-ray source</td>
			<td style="width:128px;">Advanced photon Source/ Argonne National Lab</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"><a href="http://www.aps.anl.gov/Xray_Science_Division/Optics/Beamline/">http://www.aps.anl.gov/Xray_Science_Division/Optics/Beamline/</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">LYSO Scintillator</td>
			<td>Proteus Inc</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.apace-science.com/proteus/lyso.htm#top">http://www.apace-science.com/proteus/lyso.htm#top</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Coolsnap HQ2 CCD detector</td>
			<td style="width:128px;">Photometrics</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.photometrics.com/products/ccdcams/coolsnap_hq2.php">http://www.photometrics.com/products/ccdcams/coolsnap_hq2.php</a></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">ATC 2000 UHV sputtering deposition system</td>
			<td style="width:128px;">AJA International Inc</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.ajaint.com/systems_atc.htm">http://www.ajaint.com/systems_atc.htm</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MICROPOSIT S1800 photoresist</td>
			<td style="width:128px;">Dow&#160;</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MICROPOSIT 351 developer</td>
			<td style="width:128px;">Dow&#160;</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">MA/BA6 lithography system</td>
			<td style="width:128px;">SUSS MicroTec</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.suss.com/en/products-solutions/products/mask-aligner/maba6/overview.html">http://www.suss.com/en/products-solutions/products/mask-aligner/maba6/overview.html</a></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:215px;">Spin coater WS-400-6NPPB</td>
			<td style="width:128px;">Laurell Technologies Corporation</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.laurell.com/spin-coater/?model=WS-400-6NPP-LITE">http://www.laurell.com/spin-coater/?model=WS-400-6NPP-LITE</a></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">JBX-9300FS electron beam lithography system</td>
			<td style="width:128px;">JEOL</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.jeolusa.com/PRODUCTS/PhotomaskDirectWriteLithography/ElectronBeamLithography/JBX-9500FS/tabid/245/Default.aspx">http://www.jeolusa.com/PRODUCTS/PhotomaskDirectWriteLithography/ElectronBeamLithography/JBX-9500FS/tabid/245/Default.aspx</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">CS-1701 RIE system</td>
			<td style="width:128px;">Nordson March</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.nordson.com/EN-US/DIVISIONS/MARCH/PRODUCTS/LEGACY/Pages/CS-1701-Anisotropic-RIE-Plasma-System.aspx">http://www.nordson.com/EN-US/DIVISIONS/MARCH/PRODUCTS/LEGACY/Pages/CS-1701-Anisotropic-RIE-Plasma-System.aspx</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Techni Gold 25E</td>
			<td style="width:128px;">Technic</td>
			<td style="width:119px;"></td>
			<td><a href="http://www.technic.com/eu/applications/industrial/industrial-chemistry/plating-chemistry">http://www.technic.com/eu/applications/industrial/industrial-chemistry/plating-chemistry</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Dektak-8 surface profiler</td>
			<td style="width:128px;">Bruker</td>
			<td style="width:119px;"></td>
			<td><a href="http://brukersupport.com/ProductDetail/1136">http://brukersupport.com/ProductDetail/1136</a></td>
		</tr>
		<tr height="21">
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measurement of x-ray beam coherence along multiple directions using 2-d checkerboard phase grating

A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is reported. The measurements were demonstrated at the 1-BM bending magnet beamline of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). By using a 2-D checkerboard &#960;/2 phase-shift grating, transverse coherence lengths were obtained along the vertical and horizontal directions as well as along the 45&#176; and 135&#176; directions to the horizontal direction. Following the technical details specified in this paper, interferograms were measured at different positions downstream of the phase grating along the beam propagation direction. Visibility values of each interferogram were extracted from analyzing harmonic peaks in its Fourier Transformed image. Consequently, the coherence length along each direction can be extracted from the evolution of visibility as a function of the grating-to-detector distance. The simultaneous measurement of coherence lengths in four directions helped identify the elliptical shape of the coherence area of the Gaussian-shaped X-ray source. The reported technique for multiple-direction coherence characterization is important for selecting the appropriate sample size and orientation as well as for correcting the partial coherence effects in coherence scattering experiments. This technique can also be applied for assessing coherence preserving capabilities of X-ray optics.

While detailed experimental and simulation results could be found elsewhere8, this section only shows selected results to illustrate the above measurement and data analysis procedures. Figure 1 represents the experiment setup at the APS 1-BM-B beamline. The beam size is defined by a 1&#215;1 mm2 slit placed upstream of the Double Crystal Monochromator (DCM) and 25 m from the bending magnet source. The DCM is tuned to output photon energy of 18 keV. The X-ray beam passes through seve...

Watch this Scientific Journal Video about Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating at JoVE.com

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating

The measurement protocol and data analysis procedure are given for obtaining transverse coherence of a synchrotron radiation X-ray source along four directions simultaneously using a single 2-D checkerboard phase grating. This simple technique can be applied for complete transverse coherence characterization of X-ray sources and X-ray optics.

A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is ...

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9.5K Views.  Argonne National Laboratory. The measurement protocol and data analysis procedure are given for obtaining transverse coherence of a synchrotron radiation X-ray source along four directions simultaneously using a single 2-D checkerboard phase grating. This simple technique can be applied for complete transverse coherence characterization of X-ray sources and X-ray optics.

Video: Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating

Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, spin-flip scattering) is described, using experiments on GaMnAs as a prototype III-Mn-V system.&#160; Spectrally-resolved and time-resolved experimental configurations are described, including the use of zero-background autocorrelation techniques for pulse optimization.&#160; The etching process used to prepare GaMnAs samples for four-wave mixing experiments is also highlighted.&#160; The high temporal resolution of this technique, afforded by the use of short (20 fsec) optical pulses, permits the rapid spin-flip scattering process in this system to be studied directly in the time domain, providing new insight into the strong exchange coupling responsible for carrier-mediated ferromagnetism.&#160; We also show that spectral resolution of the four-wave mixing signal allows one to extract clear signatures of (s,p)-d hybridization in this system, unlike linear spectroscopy techniques.&#160;&#160; This increased sensitivity is due to the nonlinearity of the technique, which suppresses defect-related contributions to the optical response. This method may be used to measure the time scale for coherence decay (tied to the fastest scattering processes) in a wide variety of semiconductor systems of interest for next generation electronics and optoelectronics.

The technique of femtosecond four-wave mixing is described, including spectrally-resolved and time-resolved configurations. We illustrate the utility of this technique for the investigation of crucial physical properties in the III-V diluted magnetic semiconductors, afforded by its nonlinearity and high temporal resolution.

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, ...

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO2 storage. Chemical equilibrium between the CO2, brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO2 were trapped, with a residual saturation of 0.203 &#177; 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

We present a methodology for the imaging of multiple fluid phases at reservoir conditions by the use of x-ray microtomography. We show some representative results of capillary trapping in a carbonate rock sample.

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space ...

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films

The biological uptake of plutonium (Pu) in aquatic ecosystems is of particular concern since it is an alpha-particle emitter with long half-life which can potentially contribute to the exposure of biota and humans. The diffusive gradients in thin films technique is introduced here for in-situ measurements of Pu bioavailability and speciation. A diffusion cell constructed for laboratory experiments with Pu and the newly developed protocol make it possible to simulate the environmental behavior of Pu in model solutions of various chemical compositions. Adjustment of the oxidation states to Pu(IV) and Pu(V) described in this protocol is essential in order to investigate the complex redox chemistry of plutonium in the environment. The calibration of this technique and the results obtained in the laboratory experiments enable to develop a specific DGT device for in-situ Pu measurements in freshwaters. Accelerator-based mass-spectrometry measurements of Pu accumulated by DGTs in a karst spring allowed determining the bioavailability of Pu in a mineral freshwater environment. Application of this protocol for Pu measurements using DGT devices has a large potential to improve our understanding of the speciation and the biological transfer of Pu in aquatic ecosystems.

The technique of diffusive gradients in thin films (DGT) is proposed for speciation studies of plutonium. This protocol describes diffusion experiments probing the behavior of Pu(IV) and Pu(V) in presence of organic matter. DGTs deployed in a karstic spring allow assessment of the bioavailability of Pu.

The biological uptake of plutonium (Pu) in aquatic ecosystems is of particular concern since it is an alpha-particle emitter with long half-life which can ...

Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery

We demonstrate a method for electrochemical testing of an aprotic Li-O2 battery. An aprotic Li-O2 battery is made of a Li-metal anode, an aprotic electrolyte, and an O2-breathing cathode. The aprotic electrolyte is a solution of lithium salt with aprotic solvent; and porous carbon is commonly used as the cathode substrate. To improve the performance, an electrocatalyst is deposited onto the porous carbon substrate by certain deposition methods, such as atomic layer deposition (ALD) and wet-chemistry reaction. The as-prepared cathode materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray absorption near edge structure (XANES). A Swagelok-type cell, sealed in a glass chamber filled with pure O2, is used for the electrochemical test on a battery test system. The cells are tested under either capacity-controlled mode or voltage controlled mode. The reaction products are investigated by electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and Raman spectroscopy to study the possible pathway of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). This protocol demonstrates a systematic and efficient arrangement of routine tests of the aprotic Li-O2 battery, including the electrochemical test and characterization of battery materials.

Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery

A protocol for the electrochemical testing of an aprotic Li-O2 battery with the preparation of electrodes and electrolytes and an introduction of the frequently used methods of characterization is presented here.

We demonstrate a method for electrochemical testing of an aprotic Li-O2 battery. An aprotic Li-O2 battery is made of a Li-metal anode, an aprotic ...

Dynamic Pore-scale Reservoir-condition Imaging of Reaction in Carbonates Using Synchrotron Fast Tomography

Underground storage permanence is a major concern for carbon capture and storage. Pumping CO2 into carbonate reservoirs has the potential to dissolve geologic seals and allow CO2 to escape. However, the dissolution processes at reservoir conditions are poorly understood. Thus, time-resolved experiments are needed to observe and predict the nature and rate of dissolution at the pore scale. Synchrotron fast tomography is a method of taking high-resolution time-resolved images of complex pore structures much more quickly than traditional &#181;-CT. The Diamond Lightsource Pink Beam was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 &#181;m resolution over a period of 2 hours. The images were segmented and the porosity and permeability were measured using image analysis and network extraction. Porosity increased uniformly along the length of the sample; however, the rate of increase of both porosity and permeability slowed at later times.

Synchrotron fast tomography was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 &#181;m resolution over a period of 2 h.

Underground storage permanence is a major concern for carbon capture and storage. Pumping CO2 into carbonate reservoirs has the potential to dissolve ...

Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line intensity ratios. By using a Johann spectrometer viewing the plasma, it is possible to construct profiles of plasma parameters such as density, temperature, and velocity with good spatial and time resolution. However, benchmarking atomic code modeling of X-ray spectra obtained from well-diagnosed laboratory plasmas is important to justify use of such spectra to determine plasma parameters when other independent diagnostics are not available. This manuscript presents the operation of the High Resolution X-ray Crystal Imaging Spectrometer with Spatial Resolution (HIREXSR), a high wavelength resolution spatially imaging X-ray spectrometer used to view hydrogen- and helium-like ions of medium atomic number elements in a tokamak plasma. In addition, this manuscript covers a laser blow-off system that can introduce such ions to the plasma with precise timing to allow for perturbative studies of transport in the plasma.

X-ray spectra provide a wealth of information on high temperature plasmas. This manuscript presents the operation of a high wavelength resolution spatially imaging X-ray spectrometer used to view hydrogen- and helium-like ions of medium atomic number elements in a tokamak plasma.

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line ...

Optical Trap Loading of Dielectric Microparticles In Air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.