This work was supported in part by the Washington Space Grant Consortium under Award NNX10AK64H.

Certain commercial equipment is identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the authors, nor does it imply that the equipment identified is necessarily the best available for the purpose.

ישנם מספר צעדים קריטיים בפרוטוקול שדורש קצת דיון נוסף. כאשר מודדים את אורך גל לייזר-אדום הרחוק, כפי שמתואר בשלב 2.5.3, זה חשוב כדי להבטיח את אותו המצב של פליטת לייזר-אדום הרחוק נמצא בשימוש. מצבים מרובים של אורך גל לייזר-אדום רחוק (כלומר, TEM 00, TEM 01, וכו &#39;) י?...

המדידה של תדרי לייזר-אדום הרחוק בוצעה לראשונה על ידי Hocker ועמיתים לעבודה בשנת 1967. הם מדדו את התדרים ל311 ו 337 מיקרומטר פליטות מליזר המימן ציאניד הישיר פריקה על ידי ערבובם עם הרמוניות כדי גבוהות של אות מיקרוגל בדיודה סיליקון 1. כדי למדוד תדרים גבוהים יותר, שרשרת של לייזרים והתקני ערבוב הרמוניים שימשה ליצירת ההרמוניה לייזר 2. סופו של דבר שני התייצבו פחמן דו חמצני (CO 2) לייזרים נבחרו לסנתז את ההבדל ההכרחי תדרי 3,4. היום, תדרי לייזר-אדום רחוק עד 4 THz ניתן למדוד עם טכניקה זו משתמשת בהרמונית הראשונה בלבד של תדר ההבדל שנוצר על ידי שתי התייצב CO 2 לייזרי התייחסות. פליטת לייזר תדירות גבוהה יותר גם ניתן למדוד באמצעות הרמוני השני, כגון פליטת לייזר 9 THz ממחלת הלב כלילית isotopologues מתנול 2 OH ו- CH 3 </sUB&gt; 18 OH. 5,6 במהלך השנים, המדידה מדויקת של תדרי לייזר השפיעה מספר הניסויים המדעיים 7,8 והתיר אימוץ הגדרה חדשה של המטר על ידי הוועידה הכללית של משקלים ומידות בפריז ב 1983. 9 - 11 טכניקות heterodyne, כגון אלה שתוארו, היו מועילות מאוד במדידה של תדרי לייזר-אדום הרחוק שנוצרו על ידי לייזרים מולקולריים שאוב אופטי. מאז גילויו של הלייזר המולקולרי שאוב אופטי על ידי צ&#39;אנג ו -12 גשרים, אלפי אופטיים שאוב פליטת לייזר-אדום רחוק כבר נוצרה עם מגוון רחב של אמצעי תקשורת לייזר. לדוגמא, difluoromethane (CH 2 F 2) וisotopologues לייצר מעל 250 פליטת לייזר כאשר שאוב אופטי על ידי לייזר CO 2. אורכי הגל שלהם נעים בין כ 95.6-1714.1 מיקרומטר 13. - </sעד&gt; 15 כמעט 75% מכלל פליטות לייזר אלה היו התדרים שלהם נמדדו תוך כמה הוקצו 16 spectroscopically - 18. לייזרים אלה, והתדרים למדוד במדויק, יש תפקיד מכריע בקידום ספקטרוסקופיה ברזולוציה גבוהה. הם מספקים מידע חשוב ללימודי רפאים אינפרא אדום של גזי הלייזר. לעתים קרובות תדרי לייזר אלה משמשים כדי לאמת את הניתוח של ספקטרום אינפרא אדום ורחוק אינפרה-אדום משום שהם מספקים קשרים בין רמות מדינת רטט הנרגשת שלעתים קרובות אינם נגישים ישירות מספקטרום הקליטה 19. הם גם משמשים כמקור הקרינה העיקרי ללימודים חוקרים חולפים, רדיקלים חופשיים קצרים עם טכניקת התהודה מגנטית לייזר 20. בעזרת טכניקה זו מאוד רגישה, ספקטרום זימן-רטט ro סיבובי ובאטומי פאראמגנטיים, מולקולות, ויונים מולקולריים יכול להיות recorded וניתח יחד עם היכולת לחקור את שיעורי התגובה משמשים ליצירת רדיקלים חופשיים אלה. בעבודה זו, לייזר מולקולרי שאוב אופטי, מוצגת באיור 1, נעשה שימוש כדי ליצור קרינת לייזר-אדום רחוק מdifluoromethane. מערכת זו מורכבת מגל רציף (CW) לייזר משאבה CO 2 וחלל לייזר-אדום רחוק. מראה פנימי לחלל לייזר-אדום הרחוק מפנה את קרינת לייזר CO 2 במורד צינור הנחושת המלוטש, עובר עשרים ושש השתקפויות לפני סיום בסוף של החלל, פיזור קרינת משאבה שנותרה. לכן בינוני לייזר-אדום הרחוק מתרגש באמצעות גיאומטריה שאיבה רוחבית. כדי ליצור פעולת לייזר, מספר משתנה מותאמים, כמה בו זמנית, ולאחר מכן כולם מותאמים פעם קרינת לייזר הוא ציינה. בניסוי זה, קרינת לייזר-אדום רחוק מנוטרת על ידי מתכת-insulator-מתכת (MIM) גלאי דיודה נקודת מגע. גלאי דיודה MIM שמש במשך מדידות תדר לייזר מאז 1969. 21-23 במדידות תדר לייזר, גלאי דיודה MIM הוא מיקסר הרמוני בין שתיים או יותר מקורות קרינת האירוע בדיודה. גלאי דיודה MIM מורכב מתיל טונגסטן חידד פנייה בסיס ניקל אופטי מלוטש 24. יש בסיס ניקל שכבה דקה תחמוצת טבעית שהיא שכבת הבידוד. ברגע פליטת לייזר זוהתה, אורך הגל, הקיטוב, כוחה, ולחץ הפעלה מותאם נרשמו בעוד התדר שלה נמדד באמצעות טכניקת heterodyne שלושה-לייזר 25-27 הבאים בשיטה המתוארת במקור באסמכתא. 4. איור 2 מציג את הלייזר המולקולרי שאוב אופטי עם שני לייזרי התייחסות נוספים CW CO 2 שSTA תדר העצמאימערכות bilization לנצל לטבול כבש באות הקרינה 4.3 מיקרומטר מתא התייחסות לחץ חיצוני, נמוך 28. כתב יד זה מתאר את התהליך המשמש לחיפוש פליטת לייזר-אדום רחוק, כמו גם את השיטה להערכת אורך הגל שלהם ובאופן מדויק קביעת תדירותם. ניתן למצוא פרטים בנוגע לטכניקת heterodyne שלושה-הלייזר, כמו גם את המרכיבים השונים ומאפייני הפעלה של המערכת בטבלה נוספת יחד עם אזכור 4, 25-27, 29, ו -30.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Vacuum pump</td>
			<td>Leybold</td>
			<td>Trivac D4A</td>
			<td>HE-175 oil; Quantity = 3</td>
		</tr>
		<tr>
			<td>Vacuum pump</td>
			<td>Leybold</td>
			<td>Trivac D8B or D16B</td>
			<td>Fomblin Fluid; Quantity = 1 of each</td>
		</tr>
		<tr>
			<td>Vacuum pump</td>
			<td>Leybold</td>
			<td>Trivac D25B</td>
			<td>HE-175 oil; Quantity = 1</td>
		</tr>
		<tr>
			<td>Optical chopper with controller</td>
			<td>Stanford Research Systems</td>
			<td>SR540</td>
			<td></td>
		</tr>
		<tr>
			<td>Lock-in amplifier</td>
			<td>Stanford Research Systems</td>
			<td>SR830</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrum analyzer</td>
			<td>Agilent</td>
			<td>E4407B</td>
			<td>ESA-E Series, 9 kHz to 26.5 GHz Spectrum Analyzer</td>
		</tr>
		<tr>
			<td>Amplifier&#160;</td>
			<td>Miteq</td>
			<td>AFS-44</td>
			<td>Provides amplification of signals between 2 and 18 GHz. The amplifier is powered by a Hewlett Packard triple output DC power supply, model E3630A.</td>
		</tr>
		<tr>
			<td>Amplifier&#160;</td>
			<td>Avantek</td>
			<td>AWL-1200B</td>
			<td>Provides amplification of signals less than 1.2 GHz.</td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Hewlett Packard</td>
			<td>E3630A</td>
			<td>Low voltage DC power supply for amplifier.</td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Glassman</td>
			<td>KL Series</td>
			<td>High voltage power supply for the CO2 lasers; Quantity = 2; negative polarity</td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Fluke</td>
			<td>412B</td>
			<td>High voltage power supply used with the NIST Asymmetric HV Amp</td>
		</tr>
		<tr>
			<td>Detector</td>
			<td>Judson Infrared Inc</td>
			<td>J10D</td>
			<td>For fluorescence cell; Quantity = 2</td>
		</tr>
		<tr>
			<td>CO2 laser spectrum analyzer</td>
			<td>Optical Engineering&#160;</td>
			<td>16-A</td>
			<td>Currently sold by Macken Instruments Inc.</td>
		</tr>
		<tr>
			<td>Thermal imaging plates with UV light</td>
			<td>Optical Engineering&#160;</td>
			<td></td>
			<td>Primarily used for aligning the CO2 reference lasers. Currently sold by Macken Instruments Inc.</td>
		</tr>
		<tr>
			<td>Resistors</td>
			<td>Ohmite&#160;</td>
			<td>L225J100K</td>
			<td>100 kW, 225 W. Between 4 to 6 resistors are used in each ballast system. Each CO2 laser has its own ballast system. Fans are used to cool the resistors.</td>
		</tr>
		<tr>
			<td>HV relay, SPDT</td>
			<td>CII Technologies</td>
			<td>H-17</td>
			<td>Quantity = 3; one for each CO2 laser</td>
		</tr>
		<tr>
			<td>Amplifier&#160;</td>
			<td>Princeton Applied Research</td>
			<td>PAR 113</td>
			<td>Used with fluorescence cell; Quantity = 2</td>
		</tr>
		<tr>
			<td>Oscilloscope</td>
			<td>Tektronix</td>
			<td>2235A</td>
			<td>Similar models are also used; Quantity = 2</td>
		</tr>
		<tr>
			<td>Oscilloscope/Differential amplifier</td>
			<td>Tektronix</td>
			<td>7903 oscilloscope with 7A22 differential amplifier</td>
			<td></td>
		</tr>
		<tr>
			<td>Power meter with sensor</td>
			<td>Coherent</td>
			<td>200</td>
			<td>For use below 10 W.&#160; This is the power meter shown in Figure 2.</td>
		</tr>
		<tr>
			<td>Power meter with sensor</td>
			<td>Scientech, Inc</td>
			<td>Vector S310</td>
			<td>For use below 30 W</td>
		</tr>
		<tr>
			<td>Multimeter</td>
			<td>Fluke</td>
			<td>73III</td>
			<td>Similar models are also used; Quantity = 3</td>
		</tr>
		<tr>
			<td>Data acquisition</td>
			<td>National Instruments</td>
			<td>NI cDAQ 9174 chassis with NI 9223 input module</td>
			<td>Uses LabVIEW software</td>
		</tr>
		<tr>
			<td>Simichrome polish</td>
			<td>Happich GmbH</td>
			<td></td>
			<td>Polish for the Nickel base used in the MIM diode detector. Although the Nickel base can be used immediately after polishing, a 12 hour lead time is typically recommended.</td>
		</tr>
		<tr>
			<td>Pressure gauge</td>
			<td>Wallace and Tiernan</td>
			<td>61C-1D-0050</td>
			<td>Series 300; for CO2 laser; Quantity = 3</td>
		</tr>
		<tr>
			<td>Pressure gauge with controller</td>
			<td>Granville Phillips</td>
			<td>Series 375</td>
			<td>For far-infrared laser</td>
		</tr>
		<tr>
			<td>Zirconium Oxide felt</td>
			<td>Zircar Zirconia</td>
			<td>ZYF felt</td>
			<td>Used as a beam stop</td>
		</tr>
		<tr>
			<td>Zirconium Oxide board</td>
			<td>Zircar Zirconia</td>
			<td>ZYZ-3 board</td>
			<td>Used as a beam stop; Quantity = 4</td>
		</tr>
		<tr>
			<td>Teflon sheet</td>
			<td>Scientific Commodities, Inc</td>
			<td>BB96312-1248</td>
			<td>1/32 inch thick; used for the far-infrared laser output window</td>
		</tr>
		<tr>
			<td>Polypropylene</td>
			<td>C-Line sheet protectors</td>
			<td>61003</td>
			<td>used for the far-infrared laser output window</td>
		</tr>
		<tr>
			<td>Vacuum grease</td>
			<td>Apiezon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Kepco</td>
			<td>NTC 2000</td>
			<td>PZT power supply</td>
		</tr>
		<tr>
			<td>PZT tube</td>
			<td>Morgan Advanced Materials</td>
			<td></td>
			<td>1 inch length, 1 inch outer diameter, 0.062 inch thickness, reverse polarity (positive voltage on outside); Quantity = 3</td>
		</tr>
		<tr>
			<td>ZnSe (AR coated)</td>
			<td>II-VI Inc</td>
			<td></td>
			<td>CO2 laser window (Quantity = 3), lens, and beam splitter (Quantity 3)</td>
		</tr>
		<tr>
			<td>NaCl window</td>
			<td>Edmond Optics</td>
			<td></td>
			<td>Quantity = 1</td>
		</tr>
		<tr>
			<td>CaF window</td>
			<td>Edmond Optics</td>
			<td></td>
			<td>Quantity = 2</td>
		</tr>
		<tr>
			<td>Laser mirrors and gratings</td>
			<td>Hyperfine, Inc</td>
			<td></td>
			<td>Gold-coated; includes positioning mirrors</td>
		</tr>
		<tr>
			<td>Glass laser tubes and reference cells</td>
			<td>Allen Scientific Glass</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MIM diode detector</td>
			<td>Custom Microwave, Inc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Other</td>
			<td></td>
			<td></td>
			<td>Other materials include magnetic bases, base plates, base clamps, XYZ translation stage, etc.</td>
		</tr>
	</tbody>
</table>

characterizing far-infrared laser emissions and the measurement of their frequencies

הדור והמדידה העוקבת של קרינה-אדום הרחוק מצא יישומים רבים בספקטרוסקופיה ברזולוציה גבוהה, אסטרונומיה רדיו, והדמיה Terahertz. במשך כ -45 שנים, הדור של קוהרנטית קרינה, רחוק אינפרה-אדומה הושג באמצעות הלייזר המולקולרי שאוב אופטי. ברגע שקרינת לייזר-אדום רחוק מזוהה, התדרים של פליטות לייזר אלה נמדדים באמצעות טכניקת heterodyne שלושה-לייזר. בעזרת טכניקה זו, התדירות לא ידועה מהליזר המולקולרי שאוב אופטי היא מעורבת עם תדירות ההבדל בין שני תדרי התייחסות התייצבו, אינפרא אדום. תדרי התייחסות אלה שנוצרו על ידי לייזרי פחמן דו חמצני עצמאיים, כל אחד התייצב באמצעות אות הקרינה מסלולרית התייחסות חיצונית, בלחץ נמוך. פעימת כתוצאה בין תדרי לייזר הידועים ובלתי ידועים מנוטרת על ידי גלאי דיודה נקודת מגע מתכת-מבודדת-מתכת הפלט שהוא ציין במפרטמנתח טראם. תדירות הפעימה בין פליטת לייזר אלה נמדדת לאחר מכן בשילוב עם תדרי התייחסות הידועים להסיק תדר לייזר-אדום רחוק לא ידוע. אי הוודאות וכתוצאה מכך אחד-סיגמא השבר עבור תדרי לייזר נמדדה עם טכניקה זו היא ± 5 חלקים ב 10 7. קביעה מדויקת של תדירות פליטת לייזר-אדום הרחוק היא קריטי כפי שהם משמשים לעתים קרובות כהתייחסות למדידות אחרות, כמו בגבוה חקירות ספקטרוסקופיות -resolution של רדיקלים חופשיים באמצעות תהודה מגנטית לייזר. כחלק מחקירה זו, difluoromethane, CH 2 F 2, שימש כמדיום לייזר-אדום הרחוק. בסך הכל, שמונה תדרי לייזר-אדום רחוק נמדדו בפעם הראשונה עם תדרים החל 0.359-1.273 THz. שלוש פליטות לייזר אלה התגלו במהלך חקירה זו ומדווחים עם לחצן הפעלה האופטימלי, קיטוב ביחס לCO 2 </sub&gt; לשאוב לייזר, וכוח.

כאמור, את תדירות דיווח לפליטת לייזר-אדום רחוק היא ממוצעת של לפחות עשר מדידות שבוצעו עם לפחות שתי קבוצות שונות של קווי לייזר 2 CO התייחסות. טבלה 2 מתארת ​​את הנתונים שנרשמו לפליטת 235.5 מיקרומטר לייזר בעת השימוש ב 9 P 04 CO 2 לייזר משאבה. לפליטת לייזר-...

Watch this Scientific Journal Video about Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies at JoVE.com

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

We describe the generation of far-infrared radiation using an optically pumped molecular laser along with the measurement of their frequencies with heterodyne techniques. The experimental system and techniques are demonstrated using difluoromethane (CH2F2) as the laser medium whose results include three new laser emissions and eight measured laser frequencies.

אפיון פליטות לייזר רחוק אינפרה-אדומות והמדידה של התדרים שלהם

The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and ...

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12.0K Views.  Central Washington University. We describe the generation of far-infrared radiation using an optically pumped molecular laser along with the measurement of their frequencies with heterodyne techniques. The experimental system and techniques are demonstrated using difluoromethane (CH2F2) as the laser medium whose results include three new laser emissions and eight measured laser frequencies.

Video: Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

Spatial Separation of Molecular Conformers and Clusters

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules.

We present a technique that allows the spatial separation of different conformers or clusters present in a molecular beam. An electrostatic deflector is used to separate species by their mass-to-dipole moment ratio, leading to the production of gas-phase ensembles of a single conformer or cluster stoichiometry.

הפרדה מרחבית של קונפורמרים מולקולריים ואשכולות

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold ...

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 &#181;m spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C2), cyanogen (CN), and titanium monoxide (TiO).
The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS.

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

Time-resolved atomic and diatomic molecular species are measured using LIBS. The spectra are collected at various time delays following the generation of optical breakdown plasma with Nd:YAG laser radiation&#160;and are analyzed to infer electron density and temperature.

מדידה וניתוח של מימן אטומי והמולקולרי דו האטומי ALO, C<sub&gt; 2</sub&gt;, CN, וההתפלגות מושרה הלייזר הבא TIO הספקטרום אופטית

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement ...

Design and Use of a Full Flow Sampling System (FFS) for the Quantification of Methane Emissions

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas industry faces continued scrutiny for methane emissions from across the supply chain, due to methane&#39;s relatively high global warming potential (25-84x that of carbon dioxide, according to the Energy Information Administration). Currently, a variety of techniques of varied uncertainties exists to measure or estimate methane emissions from components or facilities. Currently, only one commercial system is available for quantification of component level emissions and recent reports have highlighted its weaknesses.
In order to improve accuracy and increase measurement flexibility, we have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases based on transportation emissions measurement principles. The FFS is a modular system that consists of an explosive-proof blower(s), mass airflow sensor(s) (MAF), thermocouple, sample probe, constant volume sampling pump, laser based greenhouse gas sensor, data acquisition device, and analysis software. Dependent upon the blower and hose configuration employed, the current FFS is able to achieve a flow rate ranging from 40 to 1,500 standard cubic feet per minute (SCFM). Utilization of laser-based sensors mitigates interference from higher hydrocarbons (C2+). Co-measurement of water vapor allows for humidity correction. The system is portable, with multiple configurations for a variety of applications ranging from being carried by a person to being mounted in a hand drawn cart, on-road vehicle bed, or from the bed of utility terrain vehicles (UTVs). The FFS is able to quantify methane emission rates with a relative uncertainty of &#177; 4.4%. The FFS has proven, real world operation for the quantification of methane emissions occurring in conventional and remote facilities.

Design and Use of a Full Flow Sampling System FFS for the Quantification of Methane Emissions

We have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases from across the natural gas supply chain.

עיצוב ושימוש מערכת דגימה זרימה מלאה (FFS) עבור כימות פליטות מתאן

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas ...

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.

טוען מלכודת אופטית של דיאלקטרי microparticles באוויר

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

Generation of Size-controlled Poly (ethylene Glycol) Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. This paper proposes a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation. The polydimethylsiloxane (PDMS) chip was fabricated using the multi-layer soft lithography method. Hexadecane containing surfactant was used as the continuous phase, and PEGDA with the ultraviolet (UV) photo-initiator was the dispersed phase. Surfactants allowed the local surface tension to drop and formed a more cusped tip which promoted breaking into tiny micro-droplets. As the pressure of dispersed phase was constant, the size of droplets became smaller with increasing continuous phase pressure before dispersed phase flow was broken off. As a result, droplets with size variation from 1 &#181;m to 80 &#181;m in diameter could be selectively achieved by changing the pressure ratio in two inlet channels, and the average coefficient of variation was estimated to be below 7%. Furthermore, droplets could turn into micro-beads by UV exposure for photo-polymerization. Conjugating biomolecules on such micro-beads surface have many potential applications in the fields of biology and chemistry.

Generation of Size-controlled Poly ethylene Glycol Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Here, we present a protocol to illustrate the fabrication processes and verifying experiments of a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation.

דור של פולי שבשליטת גודל (אתילן גליקול) Diacrylate טיפות דרך דו-תלת-ממדי לזרום התמקדות Microfluidic מכשירים

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

פיתוח שיטה עבור מדעי החלל ללא מגע מכשירים ספקטרוסקופיים הדיאלקטרי של הנייר תאית

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...

Measuring Sub-23 Nanometer Real Driving Particle Number Emissions Using the Portable DownToTen Sampling System

The current particle size threshold of the European Particle Number (PN) emission standards is 23 nm. This threshold could change because future combustion engine vehicle technology may emit large amounts of sub-23 nm particles. The Horizon 2020 funded project DownToTen (DTT) developed a sampling and measurement method to characterize particle emissions in this currently unregulated size range. A PN measurement system was developed based on an extensive review of the literature and laboratory experiments testing a variety of PN measurement and sampling approaches. The measurement system developed is characterized by high particle penetration and versatility, which enables the assessment of primary particles, delayed primary particles, and secondary aerosols, starting from a few nanometers in diameter. This paper provides instruction on how to install and operate this Portable Emission Measurement System (PEMS) for Real Drive Emissions (RDE) measurements and assess particle number emissions below the current legislative limit of 23 nm.

Presented here is the DownToTen (DTT) portable emission measurement system to assess real driving automotive emissions of sub-23 nm particles.

מדידת תת-23 ננומטר פליטת חלקיק נהיגה אמיתית באמצעות מערכת הדגימה הניידת DownToTen

The current particle size threshold of the European Particle Number (PN) emission standards is 23 nm. This threshold could change because future ...

3D Printing - Evaluating Particle Emissions of a 3D Printing Pen

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament fabrication (FFF) is an inexpensive method used most frequently by consumers. Studies with 3D printers have shown that during the printing process particulate and volatile substances are released. Handheld 3D printing pens also use the FFF method but the consumer&#8217;s proximity to the 3D pens gives reason to higher exposure compared to a 3D printer. At the same time, 3D printing pens are often marketed for children who could be more sensitive to the printing emission. The aim of this study was to implement a low cost method to analyze the emissions of 3D printing pens. Polylactide (PLA) and acrylonitrile butadiene styrene (ABS) filaments of different colors were tested. In addition, filaments containing metal and carbon nanotubes (CNTs) were analyzed. An 18.5 L chamber and sampling close to the emission source was used to characterize emissions and concentrations near the breathing zone of the user.
Particle emissions and particle size distributions were measured and the potential release of metal particles and CNTs investigated. Particle number concentrations were found in a range of 105 - 106 particles/cm3, which is comparable to previous reports from 3D printers. Transmission electron microscopy (TEM) analysis showed nanoparticles of the different thermoplastic materials as well as of metal particles and CNTs. High contents of metal were observed by inductively coupled plasma mass spectrometry (ICP-MS).
These results call for a cautious use of 3D pens due to potential risk to the consumers.

This protocol presents a method to analyze the emission of 3D printing pens. Particle concentration and particle size distribution of the released particle is measured. Released particles are further analyzed with transmission electron microscopy (TEM). Metal content in filaments is quantified by inductively coupled plasma mass spectrometry (ICP-MS).

הדפסה בתלת-ממד - הערכת פליטות חלקיקים של עט הדפסה בתלת-ממד

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament ...

Solution Blow Spinning of Polymeric Nano-Composite Fibers for Personal Protective Equipment

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic resin material (binder) to form a non-woven, unidirectional laminate. While significant efforts have focused on improving the mechanical properties of the high-strength fibers, little work has been undertaken to improve the properties of the binder materials. To improve the performance of these elastomeric polymer binders, a relatively new and simple fabrication process, known as solution blow spinning, was used. This technique is capable of producing sheets or webs of fibers with average diameters ranging from the nanoscale to the microscale. To achieve this, a solution blow spinning (SBS) apparatus has been designed and built in the laboratory to fabricate non-woven fiber mats from polymer elastomer solutions.
In this study, a commonly used binder material, a styrene-butadiene-styrene block-co-polymer dissolved in tetrahydrofuran, was used to produce nanocomposite fiber mats by adding metallic nanoparticles (NPs), such as iron oxide NPs, that were encapsulated with silicon oil and thus incorporated in the fibers formed via the SBS process. The protocol described in this work will discuss the effects of the various critical parameters involved in the SBS process, including the polymer molar mass, the selection of the thermodynamically appropriate solvent, the polymer concentration in solution, and the carrier gas pressure to assist others in performing similar experiments, as well as provide guidance to optimize the configuration of the experimental setup. The structural integrity and morphology of the resultant non-woven fiber mats were examined using scanning electron microscopy (SEM) and elemental X-ray analysis via energy-dispersive X-ray spectroscopy (EDS). The goal of this study is to evaluate the effects of the various experimental parameters and material selections to optimize the structure and morphology of the SBS fiber mats.

The primary goal of this study is to describe a protocol to prepare polymeric fiber mats with consistent morphology via solution blow spinning (SBS). We aim to use SBS to develop novel, tunable, flexible polymeric fiber nanocomposites for various applications, including protective materials, by incorporating nanoparticles in a polymer-elastomer matrix.

פתרון סחיטה של סיבים ננו-מרוכבים פולימריים לציוד מגן אישי

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic ...

ייצור אטאלון פברי-פרוט ליישום בספקטרוסקופיית עקבות-גז

Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are used for their high sensitivity as well as their exceptional filtering capability. However, air-spaced etalons with high finesse are usually built by specialized facilities. Their production requires a clean room, special glass handling, and coating machinery, meaning commercially available FPEs are sold for a high price. In this article, a new and cost-effective method to fabricate fiber-coupled FPEs with standard photonic laboratory equipment is presented. The protocol should serve as a step-by-step guide for the construction and characterization of these FPEs. We hope this&#160;will enable researchers to conduct fast and cost-effective prototyping of FPEs for various fields of application. The FPE, as presented here, is used for spectroscopic applications. As shown in the representative results section via proof of principle measurements of water vapor in ambient air, this FPE has a finesse of 15, which is sufficient for the photothermal detection of trace concentrations of gases.

מחבר זרקור: ייצור של אטאלון פברי-פרוט זול, מצומד סיבים ומרווח באוויר  

This protocol describes the construction of a low-cost, discrete, fiber-coupled, and air-spaced Fabry-Perot etalon with various applications, such as in trace-gas spectroscopy. The fabrication is possible in any facility with standard optical laboratory equipment available.

ייצור אטאלון פברי-פרוט בעלות נמוכה, מצומד סיבים ומרווח באוויר

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are ...