This work was supported by JSPS KAKENHI Grant Numbers JP24750023, JP24350012, MEXT KAKENHI Grant Numbers JP26104534, JP16H00850, JP26102541, JP16H00782, and MEXT-Supported Program for the Strategic Research Foundation at Private Universities, 2015&#8211;2019.

1. Startup of electric devices
<ol>
	<li>Turn on the femtosecond Ti:sapphire laser system according to its operation manual. Wait 2 h for the laser system to warm up.</li>
	<li>Turn on the power switches of the optical chopper, the translational stage controllers, the spectrograph, the InGaAs array detector, and the computer while the system is warming up. Fill the detector&#39;s Dewar with liquid nitrogen.</li>
</ol>
2. Optical alignment of spectrometer
<ol>
	<li>Mirror adjustment (<s...

<ol>
	<li>Pol&#237;vka, T., Herek, J. L., Zigmantas, D., &#197;kerlund, H. -. E., Sundstr&#246;m, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+Observation+of+the+(Forbidden)+S1+State+in+Carotenoids.">Direct Observation of the (Forbidden) S1 State in Carotenoids.</a> Proceedings of the National Academy of Sciences of the United States of America. 96 (9), 4914-4917 (1999).</li><li>Takaya, T., Iwata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relaxation+Mechanism+of+&#946;-Carotene+from+S2+(1Bu+)+State+to+S1+(2Ag-)+State:+Femtosecond+Time-Resolved+Near-IR+Absorption+and+Stimulated+Resonance+Raman+Studies+in+900-1550+nm+Region.">Relaxation Mechanism of &#946;-Carotene from S2 (1Bu+) State to S1 (2Ag-) State: Femtosecond Time-Resolved Near-IR Absorption and Stimulated Resonance Raman Studies in 900-1550 nm Region.</a> Journal of Physical Chemistry A. 118 (23), 4071-4078 (2014).</li><li>Takaya, T., Anan, M., Iwata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vibrational+Relaxation+Dynamics+of+&#946;-Carotene+and+Its+Derivatives+with+Substituents+on+Terminal+Rings+in+Electronically+Excited+States+as+Studied+by+Femtosecond+Time-Resolved+Stimulated+Raman+Spectroscopy+in+the+Near-IR+Region.">Vibrational Relaxation Dynamics of &#946;-Carotene and Its Derivatives with Substituents on Terminal Rings in Electronically Excited States as Studied by Femtosecond Time-Resolved Stimulated Raman Spectroscopy in the Near-IR Region.</a> Physical Chemistry Chemical Physics. 20 (5), 3320-3327 (2017).</li><li>Guo, J., Ohkita, H., Benten, H., Ito, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Near-IR+Femtosecond+Transient+Absorption+Spectroscopy+of+Ultrafast+Polaron+and+Triplet+Exciton+Formation+in+Polythiophene+Films+with+Different+Regioregularities.">Near-IR Femtosecond Transient Absorption Spectroscopy of Ultrafast Polaron and Triplet Exciton Formation in Polythiophene Films with Different Regioregularities.</a> Journal of the American Chemical Society. 131 (46), (2009).</li><li>Hwang, I. -. W., 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=Carrier+Generation+and+Transport+in+Bulk+Heterojunction+Films+Processed+with+1,8-Octanedithiol+as+a+Processing+Additive.">Carrier Generation and Transport in Bulk Heterojunction Films Processed with 1,8-Octanedithiol as a Processing Additive.</a> Journal of Applied Physics. 104 (3), 033706 (2008).</li><li>Yonezawa, K., Kamioka, H., Yasuda, T., Han, L., Moritomo, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+Carrier+Formation+from+Acceptor+Exciton+in+Low-Gap+Organic+Photovoltaic.">Fast Carrier Formation from Acceptor Exciton in Low-Gap Organic Photovoltaic.</a> Applied Physics Express. 5 (4), 042302 (2012).</li><li>Takaya, T., Enokida, I., Furukawa, Y., Iwata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+Observation+of+Structure+and+Dynamics+of+Photogenerated+Charge+Carriers+in+Poly(3-hexylthiophene)+Films+by+Femtosecond+Time-Resolved+Near-IR+Inverse+Raman+Spectroscopy.">Direct Observation of Structure and Dynamics of Photogenerated Charge Carriers in Poly(3-hexylthiophene) Films by Femtosecond Time-Resolved Near-IR Inverse Raman Spectroscopy.</a> Molecules. 24 (3), 431 (2019).</li><li>Clafton, S. N., Huang, D. M., Massey, W. R., Kee, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femtosecond+Dynamics+of+Excitons+and+Hole-Polarons+in+Composite+P3HT/PCBM+Nanoparticles.">Femtosecond Dynamics of Excitons and Hole-Polarons in Composite P3HT/PCBM Nanoparticles.</a> Journal of Physical Chemistry B. 117 (16), 4626-4633 (2013).</li><li>Cook, S., Furube, A., Katoh, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+the+Excited+States+of+Regioregular+Polythiophene+P3HT.">Analysis of the Excited States of Regioregular Polythiophene P3HT.</a> Energy &amp; Environmental Science. 1 (2), 294-299 (2008).</li><li>Okino, S., Takaya, T., Iwata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femtosecond+Time-Resolved+Near-Infrared+Spectroscopy+of+Oligothiophenes+and+Polythiophene:+Energy+Location+and+Effective+Conjugation+Length+of+Their+Low-Lying+Excited+States.">Femtosecond Time-Resolved Near-Infrared Spectroscopy of Oligothiophenes and Polythiophene: Energy Location and Effective Conjugation Length of Their Low-Lying Excited States.</a> Chemistry Letters. 44 (8), 1059-1061 (2015).</li><li>Takaya, T., Iwata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+Femtosecond+Time-Resolved+Near-IR+Multiplex+Stimulated+Raman+Spectrometer+in+Resonance+with+Transitions+in+the+900-1550+nm+Region.">Development of a Femtosecond Time-Resolved Near-IR Multiplex Stimulated Raman Spectrometer in Resonance with Transitions in the 900-1550 nm Region.</a> Analyst. 141 (14), 4283-4292 (2016).</li><li>Jas, G. S., Wan, C., Johnson, C. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Picosecond+Time-Resolved+Fourier+Transform+Raman+Spectroscopy+of+9,10-Diphenylanthracene+in+the+Excited+Singlet+State.">Picosecond Time-Resolved Fourier Transform Raman Spectroscopy of 9,10-Diphenylanthracene in the Excited Singlet State.</a> Applied Spectroscopy. 49 (5), 645-649 (1995).</li><li>Jas, G. S., Wan, C., Kuczera, K., Johnson, C. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Picosecond+Time-Resolved+Fourier-Transform+Raman+Spectroscopy+and+Normal-Mode+Analysis+of+the+Ground+State+and+Singlet+Excited+State+of+Anthracene.">Picosecond Time-Resolved Fourier-Transform Raman Spectroscopy and Normal-Mode Analysis of the Ground State and Singlet Excited State of Anthracene.</a> Journal of Physical Chemistry. 100 (29), 11857-11862 (1996).</li><li>Sakamoto, A., Okamoto, H., Tasumi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Observation+of+Picosecond+Transient+Raman+Spectra+by+Asynchronous+Fourier+Transform+Raman+Spectroscopy.">Observation of Picosecond Transient Raman Spectra by Asynchronous Fourier Transform Raman Spectroscopy.</a> Applied Spectroscopy. 52 (1), 76-81 (1998).</li><li>Sakamoto, A., Matsuno, S., Tasumi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+of+Picosecond+Time-Resolved+Raman+Spectrometers+with+Near-Infrared+Excitation.">Construction of Picosecond Time-Resolved Raman Spectrometers with Near-Infrared Excitation.</a> Journal of Raman Spectroscopy. 37 (1-3), 429-435 (2006).</li><li>Sakamoto, A., Matsuno, S., Tasumi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Picosecond+Near-Infrared+Excited+Transient+Raman+Spectra+of+&#946;-Carotene+in+the+Excited+S2+State:+Solvent+Effects+on+the+in-Phase+C=C+Stretching+Band+and+Vibronic+Coupling.">Picosecond Near-Infrared Excited Transient Raman Spectra of &#946;-Carotene in the Excited S2 State: Solvent Effects on the in-Phase C=C Stretching Band and Vibronic Coupling.</a> Journal of Molecular Structure. 976 (1-3), 310-313 (2010).</li><li>Yoshizawa, M., Kurosawa, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femtosecond+Time-Resolved+Raman+Spectroscopy+Using+Stimulated+Raman+Scattering.">Femtosecond Time-Resolved Raman Spectroscopy Using Stimulated Raman Scattering.</a> Physical Review A. 61 (1), 013808 (2000).</li><li>Yoshizawa, M., Kubo, M., Kurosawa, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+Photoisomerization+in+DCM+Dye+Observed+by+New+Femtosecond+Raman+Spectroscopy.">Ultrafast Photoisomerization in DCM Dye Observed by New Femtosecond Raman Spectroscopy.</a> Journal of Luminescence. 87-89, 739-741 (2000).</li><li>Yoshizawa, M., Aoki, H., Hashimoto, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vibrational+Relaxation+of+the+2Ag&#8211;+Excited+State+in+All-Trans-&#946;-Carotene+Obtained+by+Femtosecond+Time-Resolved+Raman+Spectroscopy.">Vibrational Relaxation of the 2Ag&#8211; Excited State in All-Trans-&#946;-Carotene Obtained by Femtosecond Time-Resolved Raman Spectroscopy.</a> Physical Review B. 63 (18), 180301 (2001).</li><li>McCamant, D. W., Kukura, P., Mathies, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femtosecond+Broadband+Stimulated+Raman:+A+New+Approach+for+High-Performance+Vibrational+Spectroscopy.">Femtosecond Broadband Stimulated Raman: A New Approach for High-Performance Vibrational Spectroscopy.</a> Applied Spectroscopy. 57 (11), 1317-1323 (2003).</li><li>McCamant, D. W., Kukura, P., Yoon, S., Mathies, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femtosecond+Broadband+Stimulated+Raman+Spectroscopy:+Apparatus+and+Methods.">Femtosecond Broadband Stimulated Raman Spectroscopy: Apparatus and Methods.</a> Review of Scientific Instruments. 75 (11), 4971-4980 (2004).</li><li>Kukura, P., McCamant, D. W., Mathies, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femtosecond+Stimulated+Raman+Spectroscopy.">Femtosecond Stimulated Raman Spectroscopy.</a> Annual Review of Physical Chemistry. 58, 461-488 (2007).</li><li>Laimgruber, S., Schachenmayr, H., Schmidt, B., Zinth, W., Gilch, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Femtosecond+Stimulated+Raman+Spectrograph+for+the+Near+Ultraviolet.">A Femtosecond Stimulated Raman Spectrograph for the Near Ultraviolet.</a> Applied Physics B. 85 (4), 557-564 (2006).</li><li>Umapathy, S., Lakshmanna, A., Mallick, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+Raman+Loss+Spectroscopy.">Ultrafast Raman Loss Spectroscopy.</a> Journal of Raman Spectroscopy. 40 (3), 235-237 (2009).</li><li>Mallick, B., Lakshmanna, A., Umapathy, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+Raman+Loss+Spectroscopy+(URLS):+Instrumentation+and+Principle.">Ultrafast Raman Loss Spectroscopy (URLS): Instrumentation and Principle.</a> Journal of Raman Spectroscopy. 42 (10), 1883-1890 (2011).</li><li>Kloz, M., van Grondelle, R., Kennis, J. T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wavelength-Modulated+Femtosecond+Stimulated+Raman+Spectroscopy-Approach+towards+Automatic+Data+Processing.">Wavelength-Modulated Femtosecond Stimulated Raman Spectroscopy-Approach towards Automatic Data Processing.</a> Physical Chemistry Chemical Physics. 13 (40), 18123-18133 (2011).</li><li>Kloz, M., Wei&#223;enborn, J., Pol&#237;vka, T., Frank, H. A., Kennis, J. T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectral+Watermarking+in+Femtosecond+Stimulated+Raman+Spectroscopy:+Resolving+the+Nature+of+the+Carotenoid+S*+State.">Spectral Watermarking in Femtosecond Stimulated Raman Spectroscopy: Resolving the Nature of the Carotenoid S* State.</a> Physical Chemistry Chemical Physics. 18 (21), 14619-14628 (2016).</li><li>Kuramochi, H., Takeuchi, S., Tahara, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+Structural+Evolution+of+Photoactive+Yellow+Protein+Chromophore+Revealed+by+Ultraviolet+Resonance+Femtosecond+Stimulated+Raman+Spectroscopy.">Ultrafast Structural Evolution of Photoactive Yellow Protein Chromophore Revealed by Ultraviolet Resonance Femtosecond Stimulated Raman Spectroscopy.</a> Journal of Physical Chemistry Letters. 3 (15), 2025-2029 (2012).</li><li>Wang, 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=Dynamic+High+Pressure+Induced+Strong+and+Weak+Hydrogen+Bonds+Enhanced+by+Pre-Resonance+Stimulated+Raman+Scattering+in+Liquid+Water.">Dynamic High Pressure Induced Strong and Weak Hydrogen Bonds Enhanced by Pre-Resonance Stimulated Raman Scattering in Liquid Water.</a> Optics Express. 25 (25), 31670-31677 (2017).</li><li>Ashner, M. N., Tisdale, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+Repetition-Rate+Femtosecond+Stimulated+Raman+Spectroscopy+with+Fast+Acquisition.">High Repetition-Rate Femtosecond Stimulated Raman Spectroscopy with Fast Acquisition.</a> Optics Express. 26 (14), 18331-18340 (2018).</li><li>Quincy, T. J., Barclay, M. S., Caricato, M., Elles, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+Dynamics+in+Higher-Lying+Electronic+States+with+Resonance-Enhanced+Femtosecond+Stimulated+Raman+Spectroscopy.">Probing Dynamics in Higher-Lying Electronic States with Resonance-Enhanced Femtosecond Stimulated Raman Spectroscopy.</a> Journal of Physical Chemistry A. 122 (42), 8308-8319 (2018).</li><li>Taylor, M. 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=Delayed+Vibrational+Modulation+of+the+Solvated+GFP+Chromophore+into+a+Conical+Intersection.">Delayed Vibrational Modulation of the Solvated GFP Chromophore into a Conical Intersection.</a> Physical Chemistry Chemical Physics. 21 (19), 9728-9739 (2019).</li><li>Cassabaum, A. A., Silva, W. R., Rich, C. C., Frontiera, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Orientation+and+Polarization+Dependence+of+Ground-+and+Excited-State+FSRS+in+Crystalline+Betaine-30.">Orientation and Polarization Dependence of Ground- and Excited-State FSRS in Crystalline Betaine-30.</a> Journal of Physical Chemistry C. 123 (20), 12563-12572 (2019).</li><li>Hamaguchi, H., Iwata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Raman Spectroscopy (The Spectroscopical Society of Japan, Spectroscopy Series 1). , (2015).</li><li>Hashimoto, H., Koyama, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+C=C+Stretching+Raman+Lines+of+&#946;-Carotene+Isomers+in+the+S1+State+as+Detected+by+Pump-Probe+Resonance+Raman+Spectroscopy.">The C=C Stretching Raman Lines of &#946;-Carotene Isomers in the S1 State as Detected by Pump-Probe Resonance Raman Spectroscopy.</a> Chemical Physics Letters. 154 (4), 321-325 (1989).</li><li>Noguchi, T., Hayashi, H., Tasumi, M., Atkinson, G. 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The authors have nothing to disclose.

Crucial factors in femtosecond time-resolved near-IR multiplex stimulated Raman measurement 
To obtain time-resolved near-IR stimulated Raman spectra with a high signal-to-noise ratio, the probe spectrum should ideally have uniform intensity in the whole wavelength range. White-light continuum generation (section 2.5) is, therefore, one of the most crucial parts of time-resolved near-IR stimulated Raman experiments. In general, the probe spectrum becomes broad and flat as the intensity of the incide...

Raman spectroscopy is a powerful and versatile tool for investigating the structures of molecules in a wide variety of samples from simple gases, liquids, and solids to functional materials and biological systems. Raman scattering is significantly enhanced when the photon energy of the excitation light coincides with the electronic transition energy of a molecule. The resonance Raman effect enables us to selectively observe the Raman spectrum of a species in a sample composed of many kinds of molecules. Near-IR electronic transitions are drawing a lot of attention as a probe for investigating the excited-state dynamics of molecules with large &#960;-conjugated structures. The energy and lifetime of the lowest excited singlet state have been determined for several carotenoids, which have a long one-dimensional polyene chain1,2,3. The dynamics of neutral and charged excitations have been extensively investigated for various photoconductive polymers in films4,5,6,7, nanoparticles8, and solutions9,10,11. Detailed information on the structures of the transients will be obtainable if time-resolved near-IR Raman spectroscopy is applied to these systems. Only a few studies, however, have been reported on time-resolved near-IR Raman spectroscopy12,13,14,15,16, because the sensitivity of near-IR Raman spectrometers is extremely low. The low sensitivity principally originates from the low probability of near-IR Raman scattering. The probability of spontaneous Raman scattering is proportional to &#969;i&#969;s3, where &#969;i and &#969;s are the frequencies of the excitation light and the Raman scattering light, respectively. In addition, commercially available near-IR detectors have much lower sensitivity than CCD detectors functioning in the UV and visible regions.
Femtosecond time-resolved stimulated Raman spectroscopy has emerged as a new method of observing time-dependent changes of Raman active vibrational bands beyond the apparent Fourier-transform limit of a laser pulse17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33. Stimulated Raman scattering is generated by irradiation of two laser pulses: the Raman pump and probe pulses. Here it is assumed that the Raman pump pulse has a larger frequency than the probe pulse. When the difference between the frequencies of the Raman pump and probe pulses coincides with the frequency of a Raman active molecular vibration, the vibration is coherently excited for a large number of molecules in the irradiated volume. Nonlinear polarization induced by the coherent molecular vibration enhances the electric field of the probe pulse. This technique is particularly powerful for near-IR Raman spectroscopy, because stimulated Raman scattering can solve the problem of the sensitivity of time-resolved near-IR spontaneous Raman spectrometers. Stimulated Raman scattering is detected as intensity changes of the probe pulse. Even if a near-IR detector has a low sensitivity, stimulated Raman scattering will be detected when the probe intensity is sufficiently increased. The probability of stimulated Raman scattering is proportional to &#969;RP&#969;SRS, where &#969;RP and &#969;SRS are the frequencies of the Raman pump pulse and stimulated Raman scattering, respectively20. The frequencies for stimulated Raman scattering, &#969;RP and &#969;SRS, are equivalent to &#969;i and &#969;s for spontaneous Raman scattering, respectively. We have recently developed a femtosecond time-resolved near-IR Raman spectrometer using stimulated Raman scattering for investigating the structures and dynamics of short-lived transients photogenerated in &#960;-conjugate systems2,3,7,10. In this article, we present the technical details of our femtosecond time-resolved near-IR multiplex stimulated Raman spectrometer. Optical alignment, acquisition of time-resolved stimulated Raman spectra, and calibration and correction of recorded spectra are described. The excited-state dynamics of &#946;-carotene in toluene solution is studied as a representative application of the spectrometer.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1-Axis Translational Stage</td>
			<td>OptSigma</td>
			<td>TSD-401S</td>
			<td>Products equivalent to this are used as well; for M22, L9, and CM in Figure 1A</td>
		</tr>
		<tr>
			<td>20-cm Optical Delay Line</td>
			<td>OptSigma</td>
			<td>SGSP26-200</td>
			<td>ODL1 in Figure 1A</td>
		</tr>
		<tr>
			<td>3-Axis Translational Stage</td>
			<td>OptSigma</td>
			<td>TSD-405SL</td>
			<td>For L8 in Figure 1A</td>
		</tr>
		<tr>
			<td>3-Axis Translational Stage</td>
			<td>Suruga Seiki</td>
			<td>B72-40C</td>
			<td>For FC in Figure 1A</td>
		</tr>
		<tr>
			<td>5-cm Optical Delay Line</td>
			<td>PMT</td>
			<td>HRS-0050</td>
			<td>ODL2 in Figure 1A</td>
		</tr>
		<tr>
			<td>Al Concave Mirror</td>
			<td>Thorlabs</td>
			<td>CM254-050-G01</td>
			<td>Focal length: 50 mm; CM in Figure 1A</td>
		</tr>
		<tr>
			<td>Base Plate</td>
			<td>Suruga Seiki</td>
			<td>A21-6</td>
			<td>Products equivalent to this are used as well; for M1-M32, BS1-BS3, L1-L10, I1-I17, P1-P2, HWP1-3, F1-F3, VND1-VND2, OC, BPF, HS, BBO, SP, CM, and FC in Figure 1A</td>
		</tr>
		<tr>
			<td>BBO Crystal</td>
			<td>EKSMA Optics</td>
			<td>-</td>
			<td>Type 1, &#952; = 23.2 deg; BBO in Figure 1A</td>
		</tr>
		<tr>
			<td>BK7 Plano-Concave Lens</td>
			<td>OptSigma</td>
			<td>SLB-25.4-50NIR2</td>
			<td>Focal length: 50 mm; IR anti-reflection coating; L6 in Figure 1A</td>
		</tr>
		<tr>
			<td>BK7 Plano-Convex Lens</td>
			<td>OptSigma</td>
			<td>SLB-25.4-150PIR2</td>
			<td>Focal length: 150 mm; IR anti-reflection coating; L2, L3, L5 in Figure 1A</td>
		</tr>
		<tr>
			<td>BK7 Plano-Convex Lens</td>
			<td>OptSigma</td>
			<td>SLB-25.4-100PIR2</td>
			<td>Focal length: 100 mm; IR anti-reflection coating; L4 in Figure 1A</td>
		</tr>
		<tr>
			<td>BK7 Plano-Convex Lens</td>
			<td>OptSigma</td>
			<td>SLB-25.4-200PIR2</td>
			<td>Focal length: 200 mm; IR anti-reflection coating; L7 in Figure 1A</td>
		</tr>
		<tr>
			<td>Broadband Dielectric Mirror</td>
			<td>OptSigma</td>
			<td>TFMS-25.4C05-2/7</td>
			<td>M22-M25, M28, M29 in Figure 1A</td>
		</tr>
		<tr>
			<td>Broadband Dielectric Mirror</td>
			<td>Precision Photonics (Advanced Thin Films)</td>
			<td>-</td>
			<td>M26, M27, M30-M32 in Figure 1A</td>
		</tr>
		<tr>
			<td>Broadband Half-Wave Plate</td>
			<td>CryLight</td>
			<td>-</td>
			<td>HWP3 in Figure 1A</td>
		</tr>
		<tr>
			<td>Color Glass Filter</td>
			<td>HOYA</td>
			<td>IR85</td>
			<td>F1 in Figure 1A</td>
		</tr>
		<tr>
			<td>Color Glass Filter</td>
			<td>HOYA</td>
			<td>RM100</td>
			<td>F2 in Figure 1A</td>
		</tr>
		<tr>
			<td>Color Glass Filter</td>
			<td>Schott</td>
			<td>BG39</td>
			<td>F3 in Figure 1A</td>
		</tr>
		<tr>
			<td>Computer</td>
			<td>Dell</td>
			<td>Vostro 200 Mini Tower</td>
			<td>OS: Windows XP</td>
		</tr>
		<tr>
			<td>Cyclohexane</td>
			<td>Kanto Kagaku</td>
			<td>07547-1B</td>
			<td>HPLC grade</td>
		</tr>
		<tr>
			<td>Data Analysis Software</td>
			<td>Wavemetrics</td>
			<td>Igor Pro 8</td>
			<td></td>
		</tr>
		<tr>
			<td>Dielectric Beamsplitter</td>
			<td>LAYERTEC</td>
			<td>-</td>
			<td>Reflection : Transmission = 2 : 1; BS1 in Figure 1A</td>
		</tr>
		<tr>
			<td>Dielectric Beamsplitter</td>
			<td>LAYERTEC</td>
			<td>-</td>
			<td>Reflection : Transmission = 1 : 1; BS2, BS3 in Figure 1A</td>
		</tr>
		<tr>
			<td>Dielectric Mirror</td>
			<td>Precision Photonics 
			(Advanced Thin Films)</td>
			<td>-</td>
			<td>M1-M8 in Figure 1A</td>
		</tr>
		<tr>
			<td>Digital Oscilloscope</td>
			<td>Tektronix</td>
			<td>TDS3054B</td>
			<td>500 MHz, 5 GS/s</td>
		</tr>
		<tr>
			<td>Elastomer Tube</td>
			<td>-</td>
			<td>-</td>
			<td>Figure 1E</td>
		</tr>
		<tr>
			<td>Femtosecond Ti:sapphire Oscillator</td>
			<td>Coherent</td>
			<td>Vitesse 800-2</td>
			<td>Wavelength: 800 nm, pulse duration: 100 fs, average power: 280 mW, repetition rate: 80 MHz; included in Ti:S in Figure 1A</td>
		</tr>
		<tr>
			<td>Femtosecond Ti:sapphire Regenerative Amplifier</td>
			<td>Coherent</td>
			<td>Legend-Elite-F-HE</td>
			<td>Wavelength: 800 nm, pulse duration: 100 fs, pulse energy: 3.5 mJ, repetition rate: 1 kHz; included in Ti:S in Figure 1A</td>
		</tr>
		<tr>
			<td>Film Polarizer</td>
			<td>OptSigma</td>
			<td>SPFN-30C-26</td>
			<td>P1 in Figure 1A</td>
		</tr>
		<tr>
			<td>Glan-Taylor Prism</td>
			<td>OptSigma</td>
			<td>GYPB-10-10SN-3/7</td>
			<td>P2 in Figure 1A</td>
		</tr>
		<tr>
			<td>Gold Mirror</td>
			<td>OptSigma</td>
			<td>TFG-25C05-10</td>
			<td>M9-M21 in Figure 1A</td>
		</tr>
		<tr>
			<td>Half-Wave Plate</td>
			<td>OptSigma</td>
			<td>WPQ-7800-2M</td>
			<td>HWP1 in Figure 1A</td>
		</tr>
		<tr>
			<td>Harmonic Separator</td>
			<td>Coherent</td>
			<td>TOPAS-C HRs 410-540 nm</td>
			<td>HS in Figure 1A</td>
		</tr>
		<tr>
			<td>InGaAs Array Detector</td>
			<td>Horiba</td>
			<td>Symphony-IGA-512X1-50-1700-1LS</td>
			<td>512 ch, Liquid nitrogen cooled</td>
		</tr>
		<tr>
			<td>InGaAs PIN Photodiode</td>
			<td>Hamamatsu Photonics</td>
			<td>G10899-01K</td>
			<td></td>
		</tr>
		<tr>
			<td>IR Half-Wave Plate</td>
			<td>OptiSource</td>
			<td>-</td>
			<td>HWP2 in Figure 1A</td>
		</tr>
		<tr>
			<td>Iris</td>
			<td>Suruga Seiki</td>
			<td>F74-3N</td>
			<td>Products equivalent to this are used as well; I1-I17 in Figure 1A</td>
		</tr>
		<tr>
			<td>Lens Holder</td>
			<td>OptSigma</td>
			<td>LHF-25.4S</td>
			<td>Products equivalent to this are used as well; for L1-L10 in Figure 1A</td>
		</tr>
		<tr>
			<td>Magnetic Gear Pump</td>
			<td>Micropump</td>
			<td>184-415</td>
			<td></td>
		</tr>
		<tr>
			<td>Mirror Mount</td>
			<td>Siskiyou</td>
			<td>IM100.C2M6R</td>
			<td>Products equivalent to this are used as well; for M1-M32, BS1-BS3, BBO, CM in Figure 1A</td>
		</tr>
		<tr>
			<td>near-IR phosphor card</td>
			<td>Thorlabs</td>
			<td>VRC2</td>
			<td></td>
		</tr>
		<tr>
			<td>Nut</td>
			<td>-</td>
			<td>-</td>
			<td>Figure 1E, M4; purchased from a DIY store</td>
		</tr>
		<tr>
			<td>Optical Chopper</td>
			<td>New Focus</td>
			<td>3501</td>
			<td>OC in Figure 1A</td>
		</tr>
		<tr>
			<td>Optical Parametric Amplifier</td>
			<td>Coherent</td>
			<td>OPerA-F</td>
			<td>OPA1 in Figure 1A</td>
		</tr>
		<tr>
			<td>Optical Parametric Amplifier</td>
			<td>Coherent</td>
			<td>TOPAS-C</td>
			<td>OPA2 in Figure 1A</td>
		</tr>
		<tr>
			<td>Polarizer Holder</td>
			<td>OptSigma</td>
			<td>PH-30-ARS</td>
			<td>Products equivalent to this are used as well; for P1-P2 and HWP1-3 In Figure 1A</td>
		</tr>
		<tr>
			<td>Polyfluoroacetate Tube</td>
			<td>-</td>
			<td>-</td>
			<td>Figure 1E</td>
		</tr>
		<tr>
			<td>Post Holder</td>
			<td>OptSigma</td>
			<td>BRS-12-80</td>
			<td>Products equivalent to this are used as well; for M1-M32, BS1-BS3, L1-L10, I1-I17, P1-P2, HWP1-3, F1-F3, VND1-VND2, OC, BPF, HS, BBO, SP, CM, and FC in Figure 1A</td>
		</tr>
		<tr>
			<td>Quartz Flow Cell</td>
			<td>Tosoh Quartz</td>
			<td>T-70-UV-2</td>
			<td>FC in Figure 1A</td>
		</tr>
		<tr>
			<td>Quartz Plano-Concave Lens</td>
			<td>OptSigma</td>
			<td>SLSQ-25-50N</td>
			<td>Focal length: 50 mm; L8 in Figure 1A</td>
		</tr>
		<tr>
			<td>Quartz Plano-Convex Lens</td>
			<td>OptSigma</td>
			<td>SLSQ-25-100P</td>
			<td>Focal length: 100 mm; L1, L9 in Figure 1A</td>
		</tr>
		<tr>
			<td>Quartz Plano-Convex Lens</td>
			<td>OptSigma</td>
			<td>SLSQ-25-220P</td>
			<td>Focal length: 220 mm; L10 in Figure 1A</td>
		</tr>
		<tr>
			<td>Sapphire Plate</td>
			<td>Pier Optics</td>
			<td>-</td>
			<td>3 mm thick; SP in Figure 1A</td>
		</tr>
		<tr>
			<td>Si PIN Photodiode</td>
			<td>Hamamatsu Photonics</td>
			<td>S3883</td>
			<td></td>
		</tr>
		<tr>
			<td>Single Spectrograph</td>
			<td>Horiba Jobin Yvon</td>
			<td>iHR320</td>
			<td>Focal length: 32 cm</td>
		</tr>
		<tr>
			<td>Stainless Steel Rod</td>
			<td>Suruga Seiki</td>
			<td>A41-100</td>
			<td>Products equivalent to this are used as well; for M1-M32, BS1-BS3, L1-L10, I1-I17, P1-P2, HWP1-3, F1-F3, VND1-VND2, OC, BPF, HS, BBO, SP, CM, and FC in Figure 1A</td>
		</tr>
		<tr>
			<td>Stainless Steel Rod</td>
			<td>Newport</td>
			<td>J-SP-2</td>
			<td>Figure 1E</td>
		</tr>
		<tr>
			<td>Toluene</td>
			<td>Kanto Kagaku</td>
			<td>40180-1B</td>
			<td>HPLC grade</td>
		</tr>
		<tr>
			<td>U-Shaped Steel Plate</td>
			<td>-</td>
			<td>-</td>
			<td>Figure 1E; purchased from a DIY store</td>
		</tr>
		<tr>
			<td>Variable Neutral Density Filter (with a holder)</td>
			<td>OptSigma</td>
			<td>NDHN-100</td>
			<td>VND1 in Figure 1A</td>
		</tr>
		<tr>
			<td>Variable Neutral Density Filter (with a holder)</td>
			<td>OptSigma</td>
			<td>NDHN-U100</td>
			<td>VND2 in Figure 1A</td>
		</tr>
		<tr>
			<td>Visual Programming Language</td>
			<td>National Instruments</td>
			<td>LabVIEW 2009</td>
			<td>The control software in this study is programmed in LabVIEW 2009</td>
		</tr>
		<tr>
			<td>Volume-Grating Bandpass Filter</td>
			<td>OptiGrate</td>
			<td>BPF-1190</td>
			<td>BPF in Figure 1A</td>
		</tr>
		<tr>
			<td>&#946;-Carotene</td>
			<td>Wako Pure Chemical Industries</td>
			<td>035-05531</td>
			<td></td>
		</tr>
	</tbody>
</table>

ultrafast time-resolved near-ir stimulated raman measurements of functional &#960;-conjugate systems

Femtosecond time-resolved stimulated Raman spectroscopy is a promising method of observing the structural dynamics of short-lived transients with near infrared (near-IR) transitions, because it can overcome the low sensitivity of spontaneous Raman spectrometers in the near-IR region. Here, we describe technical details of a femtosecond time-resolved near-IR multiplex stimulated Raman spectrometer that we have recently developed. A description of signal generation and optimization, measurement, data acquisition, and calibration and correction of recorded data is provided as well. We present an application of our spectrometer to analyze the excited-state dynamics of &#946;-carotene in toluene solution. A C=C stretch band of &#946;-carotene in the second lowest excited singlet (S2) state and the lowest excited singlet (S1) state is clearly observed in the recorded time-resolved stimulated Raman spectra. The femtosecond time-resolved near-IR stimulated Raman spectrometer is applicable to the structural dynamics of &#960;-conjugate systems from simple molecules to complex materials.

Femtosecond time-resolved near-IR stimulated Raman spectroscopy was applied to &#946;-carotene in toluene solution. The concentration of the sample was 1 x 10-4 mol dm-3. The sample was photoexcited by the actinic pump pulse at 480 nm with a pulse energy of 1 &#956;J. Time-resolved stimulated Raman spectra of &#946;-carotene in toluene are shown in Figure 2A. The raw spectra contained strong Raman bands of the solvent toluene and a weak Raman band of &#...

Watch this Scientific Journal Video about Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional Ï€-conjugate Systems at JoVE.com

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional &amp;#960;-conjugate Systems

Details of signal generation and optimization, measurement, data acquisition, and data handling for a femtosecond time-resolved near-IR stimulated Raman spectrometer are described. A near infrared stimulated Raman study on the excited-state dynamics of &#946;-carotene in toluene is shown as a representative application.

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional &#960;-conjugate Systems

Femtosecond time-resolved stimulated Raman spectroscopy is a promising method of observing the structural dynamics of short-lived transients with near ...

Our protocol is particularly powerful for looking into the structure and dynamics of pi-conjugated molecules in the initial stage of chemical and biochemical reactions. This technique has a little bit higher sensitivity and makes the measurement time shorter than conventional time-resolved spontaneous Raman spectroscopy in the near-infrared with detectors available today. To begin, complete the optical setup as shown here.First, align the laser beam. With the titanium sapphire laser turned on and warmed up, place a business card behind iris two to act as a screen. Adjust mirror one until the beam passes through the center of the iris.Then, adjust mirror two until the laser beam passes through the center of iris two. Once aligned, confirm that the beam passes through the centers of both iris one and iris two simultaneously. With the laser properly aligned, begin to align the optical delay line.First, move the stage toward mirror two as far as it can go using the direction button of the stage controller. Next, adjust mirror one until the beam passes through the center of iris one. Then, move the stage as far away as it can go from mirror two.Adjust mirror two until the beam passes through the center of iris one. Now, move the stage as close as possible to the beam input and confirm that the beam still passes through the center of iris one. Next, remove iris one from the position of mirror three and place mirrors three and four on the optical delay line.Adjust mirrors three and four until the beam passes through the center of iris two. With the variable neutral density filter in the incident beam path, place a business card behind the sapphire plate as a screen. Turn the filter to gradually increase the power of the transmitted beam until a yellow white spot is observed on the screen.Then, turn the filter further in the same direction very carefully until a purple ring surrounds the yellow white spot on the screen. Next, to align the Raman pump beam, place the volume grading reflective bandpass filter in the output beam path of the optical parametric amplifier. Adjust the bandpass filter and mirror 17 using a near-IR sensor card in order to observe the beam spot.To begin optimizing the probe spectrum, run continuous measurements and maximize detector counts on the display. To accomplish this, gradually rotate half wave plate one. Then, gradually increase the intensity of the incident pulse by rotating variable optical density filter one.Do this until the maximal and minimal detector counts reach around 30, 000 and 4, 000 respectively. If a large oscillatory pattern starts to be observed, rotate the variable optical density filter in the opposite direction until the pattern disappears. For set up for spatial overlap, place the optical chopper in the Raman pump beam path.Then, place a near-IR sensor card at the sample position. Adjust the direction of the Raman pump beam by adjusting mirror 21 until the spots of the Raman pump and probe beams fully overlap with each other. To set up for the temporal overlap, place an indium gallium arsenide pin photodiode at the sample position where the Raman pump and probe beams spatially overlap with each other.Next, connect the signal output of the photodiode to a 500 megahertz five giga samples per second digital oscilloscope in order to monitor when the Raman pump and probe pulses arrive at the same position. Set the horizontal scale of the oscilloscope to be one nanosecond per division and read the peak time of the signal intensity for the Raman pump and probe pulses blocking the other pulse. Attach the inlet and outlet tubes of the magnetic gear pump to a bottle containing 30 milliliters of cyclohexane and begin flowing cyclohexane as described in the text protocol.Run continuous measurements and check if the stimulated Raman bands of cyclohexane are observed in the display. The strongest band of cyclohexane appears at the 55th through 58th pixels when the center wavelength is set at 1, 410 nanometers. Once the stimulated Raman bands are detected, maximize the band intensities in the display.Accomplish this by iteratively readjusting mirror 21, the rotational phase of the optical chopper, and the position of optical delay line two. Run a single measurement and save the spectrum as a text file. Then, remove the toluene from the reservoir and attach the inlet/outlet tubes of the magnetic gear pump to a bottle containing 25 milliliters of a toluene solution with 1X times 10 to the negative four moles per liter of beta-carotene.Then, start flowing the sample solution. Next, place the optical chopper in the actinic pump beam path. Move the beam dump from the path of the actinic pump beam to that of the Raman pump beam.Then, spatially overlap the actinic pump and probe beams at the sample position using a business card instead of the near-IR sensor card. Run continuous measurements and check if the transient absorption of beta-carotene is observed in the display. The absorption band appears with a shape decreasing monotonically toward longer wavelengths or with two maxima at around the zero and 511th pixels.Maximize the absorption intensity by readjusting mirror 32 once the transient absorption band is detected. Stop the continuous measurements and then decrease the position of the optical delay line one until the transient absorption fully disappears. Place the optical chopper in the Raman pump beam path and remove the beam dump from the Raman pump beam path.Then, run a time-resolved experiment as described in the text protocol selecting SK stage from the dropdown menu. Enter the starting position of range A to be smaller by around 50 microns compared to the position where the transient absorption signal disappeared following the measurement of time-resolved absorption spectra. Femtosecond time-resolved near-IR stimulated Raman spectroscopy was applied to beta-carotene and toluene solution.The spectra of beta-carotene and toluene is shown here. The raw spectra contained strong Raman bands of the solvent toluene and a weak Raman band of beta-carotene in the ground state as well as Raman bands of photoexcited beta-carotene. Shown here are the same spectra but subtracted using the stimulated Raman spectrum of the same solution at one picosecond before photoexcitation.The spectra after the subtraction showed distorted baselines that are caused by absorption of photoexcited beta-carotene and/or other nonlinear optical processes. The baselines became flat after they were corrected with polynomial functions. In this figure, the time-resolved stimulated Raman spectra of beta-carotene showed two strong bands in the 1, 400 to 1, 800 inverse centimeter region.A broad stimulated Raman band at zero picoseconds was assigned to the in-phase C double bond C stretch vibration of S2 beta-carotene. Its peak position was estimated to be at 1, 556 inverse centimeters. The in-phase C double bond C stretch band of S1 beta-carotene appeared as the S2 C double bond C stretch band decayed.The peak position of the S1 C double bond C stretch band was upshifted by eight inverse centimeters from 0.12 to five picoseconds. It is important to try and adjust the direction of the Raman pump beam again and again until the spots of the Raman pump and probe beams fully overlap with each other to find the stimulated Raman bands of cyclohexane. This procedure can be immediately used for other femtosecond time-resolved experiments in order to look more deeply into chemical reaction dynamics.This procedure will allow for new questions to be answered as researchers explore the chemistry of pi-conjugated molecules. While performing this procedure, don't forget to put safety glasses on to protect your eyes from strong laser light. This includes the scatter light.

ultrafast-time-resolved-near-ir-stimulated-raman-measurements

Research

JoVE Journal

Chemistry

7.0K vues.  Gakushuin University. Notre protocole est particulièrement puissant pour examiner la structure et la dynamique des molécules conjuguées au pi au stade initial des réactions chimiques et biochimiques. Cette technique a une sensibilité un peu plus élevée et rend le temps de mesure plus court que la spectroscopie raman spontanée résolue dans le temps conventionnel dans le proche infrarouge avec des détecteurs disponibles aujourd’hui. Pour commencer, complétez la configuration optique comme indiqué ici.