151
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152
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Spillane KM, Dasgupta J, Mathies RA. Conformational homogeneity and excited-state isomerization dynamics of the bilin chromophore in phytochrome Cph1 from resonance Raman intensities. Biophys J 2012; 102:709-17. [PMID: 22325295 DOI: 10.1016/j.bpj.2011.11.4019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 11/23/2011] [Accepted: 11/28/2011] [Indexed: 11/30/2022] Open
Abstract
The ground-state structure and excited-state isomerization dynamics of the P(r) and P(fr) forms of phytochrome Cph1 are investigated using resonance Raman intensity analysis. Electronic absorption and stimulated resonance Raman spectra of P(r) and P(fr) are presented; vibronic analysis of the Raman intensities and absorption spectra reveals that both conformers exist as a single, homogeneous population of molecules in the ground state. The homogeneous and inhomogeneous contributions to the overall electronic broadening are determined, and it is found that the broadening is largely homogeneous in nature, pointing to fast excited-state decay. Franck-Condon displacements derived from the Raman intensity analysis reveal the initial atomic motions in the excited state, including the highly displaced, nontotally symmetric torsional and C(15)-H HOOP modes that appear because of symmetry-reducing distortions about the C(14)-C(15) and C(15)=C(16) bonds. P(fr) is especially well primed for ultrafast isomerization and torsional Franck-Condon analysis predicts a <200 fs P(fr) → P(r) isomerization. This time is significantly faster than the observed 700 fs reaction time, indicating that the P(fr) S(1) surface has a D-ring rotational barrier caused by steric interactions with the protein.
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Affiliation(s)
- Katelyn M Spillane
- Department of Chemistry, University of California, Berkeley, California, USA
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153
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Challa JR, Du Y, McCamant DW. Femtosecond stimulated Raman spectroscopy using a scanning multichannel technique. APPLIED SPECTROSCOPY 2012; 66:227-232. [PMID: 22449287 DOI: 10.1366/11-06457] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A scanning multichannel technique (SMT) has been implemented in femtosecond stimulated Raman spectroscopy (FSRS). By combining several FSRS spectra detected at slightly different positions of the spectrograph via SMT, we have eliminated the systematic noise patterns ("fixed pattern noise") due to the variation in sensitivity and noise characteristics of the individual charge-coupled device (CCD) pixels. In nonresonant FSRS, solvent subtraction can effectively remove the systematic noise pattern even without SMT. However, in the case of resonant FSRS, we show that a similar solvent subtraction procedure is ineffective at removing the noise patterns without SMT. Application of SMT results in averaged FSRS spectra with improved signal-to-noise ratios that approach the shot-noise limit.
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Affiliation(s)
- J Reddy Challa
- Department of Chemistry, University of Rochester, 120 Trustee Rd., Rochester, New York 14627, USA
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154
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Frontiera RR, Fang C, Dasgupta J, Mathies RA. Probing structural evolution along multidimensional reaction coordinates with femtosecond stimulated Raman spectroscopy. Phys Chem Chem Phys 2012; 14:405-14. [DOI: 10.1039/c1cp22767j] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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155
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Hoffman DP, Mathies RA. Photoexcited structural dynamics of an azobenzene analog 4-nitro-4′-dimethylamino-azobenzene from femtosecond stimulated Raman. Phys Chem Chem Phys 2012; 14:6298-306. [DOI: 10.1039/c2cp23468h] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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156
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Alberding BG, Chisholm MH, Gustafson TL. Detection of the singlet and triplet MM δδ* states in quadruply bonded dimetal tetracarboxylates (M = Mo, W) by time-resolved infrared spectroscopy. Inorg Chem 2011; 51:491-8. [PMID: 22129155 DOI: 10.1021/ic201957a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The compounds M(2)(O(2)C(t)Bu)(4) and M(2)(O(2)CC(6)H(5))(4), where M = Mo or W, have been examined by femtosecond time-resolved IR (fs-TRIR) spectroscopy in tetrahydrofuran with excitation into the singlet metal-to-ligand charge-transfer ((1)MLCT) band. In the region from 1500 to 1600 cm(-1), a long-lived excited state (>2 ns) has been detected for the compounds M(2)(O(2)C(t)Bu)(4) and Mo(2)(O(2)C-C(6)H(5))(4) with an IR absorption at ~1540 cm(-1) assignable to the asymmetric CO(2) stretch, ν(as)(CO(2)), of the triplet metal-metal δ-δ star ((3)MM δδ*) state. The fs-TRIR spectra of W(2)(O(2)C-C(6)H(5))(4) are notably different and are assigned to decay of the MLCT states. In (3)MM δδ*, the removal of an electron from the δ orbital reduces MM δ to CO(2) π* back-bonding and causes a shift of ν(as)(CO(2)) to higher energy by ~30-60 cm(-1), depending on the metal. TRIR spectroscopy also provides evidence for M(2)(O(2)C(t)Bu)(4), where M = Mo or W, having MM δδ* S(1) states with ν(as)(CO(2)) distinct from those of the (3)MM δδ* states.
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Affiliation(s)
- Brian G Alberding
- Department of Chemistry, The Ohio State University, 100 West 18th Avemue, Columbus, Ohio 43210-1185, USA
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157
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158
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Qiu X, Li X, Niu K, Lee SY. Inverse Raman bands in ultrafast Raman loss spectroscopy. J Chem Phys 2011; 135:164502. [DOI: 10.1063/1.3653940] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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159
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Sahoo SK, Umapathy S, Parker AW. Time-resolved resonance Raman spectroscopy: exploring reactive intermediates. APPLIED SPECTROSCOPY 2011; 65:1087-115. [PMID: 21986070 DOI: 10.1366/11-06406] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The study of reaction mechanisms involves systematic investigations of the correlation between structure, reactivity, and time. The challenge is to be able to observe the chemical changes undergone by reactants as they change into products via one or several intermediates such as electronic excited states (singlet and triplet), radicals, radical ions, carbocations, carbanions, carbenes, nitrenes, nitrinium ions, etc. The vast array of intermediates and timescales means there is no single "do-it-all" technique. The simultaneous advances in contemporary time-resolved Raman spectroscopic techniques and computational methods have done much towards visualizing molecular fingerprint snapshots of the reactive intermediates in the microsecond to femtosecond time domain. Raman spectroscopy and its sensitive counterpart resonance Raman spectroscopy have been well proven as means for determining molecular structure, chemical bonding, reactivity, and dynamics of short-lived intermediates in solution phase and are advantageous in comparison to commonly used time-resolved absorption and emission spectroscopy. Today time-resolved Raman spectroscopy is a mature technique; its development owes much to the advent of pulsed tunable lasers, highly efficient spectrometers, and high speed, highly sensitive multichannel detectors able to collect a complete spectrum. This review article will provide a brief chronological development of the experimental setup and demonstrate how experimentalists have conquered numerous challenges to obtain background-free (removing fluorescence), intense, and highly spectrally resolved Raman spectra in the nanosecond to microsecond (ns-μs) and picosecond (ps) time domains and, perhaps surprisingly, laid the foundations for new techniques such as spatially offset Raman spectroscopy.
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Affiliation(s)
- Sangram Keshari Sahoo
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560012, India
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160
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Dang NC, Bolme CA, Moore DS, McGrane SD. Femtosecond stimulated Raman scattering picosecond molecular thermometry in condensed phases. PHYSICAL REVIEW LETTERS 2011; 107:043001. [PMID: 21866997 DOI: 10.1103/physrevlett.107.043001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate the capability of femtosecond stimulated Raman scattering (FSRS) data to measure the temperature of condensed matter at the molecular vibrational level. We report the temperature dependence of Raman loss to Raman gain ratios for low frequency modes (<300 cm(-1)) in a CaCO3 single crystal from cryogenic to room temperature, which is shown to be in agreement with theoretical predictions. We also report the measurements of nonequilibrium time evolution of mode specific vibrational temperatures in the CaCO3 single crystal to demonstrate that FSRS can measure temperature on picosecond time scales. Finally, we point out the unique origin of this temperature dependent anti-Stokes to Stokes ratio in stimulated Raman, which is not present in other coherent Raman spectroscopies. These measurements require no material dependent parameters or prior calibration.
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Affiliation(s)
- N C Dang
- Shock and Detonation Physics Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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161
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McCamant DW. Re-evaluation of rhodopsin's relaxation kinetics determined from femtosecond stimulated Raman lineshapes. J Phys Chem B 2011; 115:9299-305. [PMID: 21650454 DOI: 10.1021/jp2028164] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This work presents a theoretical treatment of the vibrational line shape generated in a femtosecond stimulated Raman spectroscopy (FSRS) experiment under conditions in which the probed vibration undergoes a significant frequency shift during its free induction decay. This theory is applied to simulate the FSRS lineshapes previously observed in rhodopsin (Kukura et al. Science 2005, 310, 1006). The previously determined relaxation times for formation of the trans-photoproduct of rhodopsin were calculated using an incorrect equation for the time dependence of the observed frequency shifts. Here the data are reanalyzed by calculation of the corrected frequency sweep occurring during the vibrational free induction decay. It is shown that the calculated frequency shifts and general conclusions of the original work are sound but that the coherent vibrational frequency shifts of the C(10), C(11), and C(12) hydrogen-out-of-plane vibrations occur with a 140 fs time constant rather than the previously reported 325 fs time constant. This time constant provides an important constraint for models of the dynamics of the cis to trans isomerization process.
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Affiliation(s)
- David W McCamant
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, USA.
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162
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Kovalenko SA, Dobryakov AL, Ernsting NP. An efficient setup for femtosecond stimulated Raman spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:063102. [PMID: 21721669 DOI: 10.1063/1.3596453] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present an efficient and robust setup for femtosecond stimulated Raman (FSR) spectroscopy with 60 fs and 10 cm(-1) resolution. Raman pulses of 0.5-5 ps are tunable between 450-750 nm with energies 1-10 μJ. Experimental features of the setup, signal processing, and data treatment are discussed in detail to be readily reproduced in other labs. The setup is tested by measuring FSR spectra of stilbene in solution.
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Affiliation(s)
- S A Kovalenko
- Department of Chemistry, Humboldt Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany.
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163
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Frontiera RR, Henry AI, Gruenke NL, Van Duyne RP. Surface-Enhanced Femtosecond Stimulated Raman Spectroscopy. J Phys Chem Lett 2011; 2:1199-203. [PMID: 26295326 DOI: 10.1021/jz200498z] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) and femtosecond stimulated Raman spectroscopy (FSRS) have revolutionized the Raman spectroscopy field. SERS provides spectroscopic detection of single molecules, and FSRS enables the acquisition of Raman spectra on the ultrafast time scale of molecular motion. Here, we present the first successful combination of these two techniques, demonstrating surface-enhanced femtosecond stimulated Raman spectroscopy (SE-FSRS) using gold nanoantennas with embedded reporter molecules. Using a picosecond Raman and femtosecond probe pulse, the time- and ensemble-averaged enhancement factor is estimated to be in the range of 10(4)-10(6). We report the line shapes, power dependence, and magnitude of the SE-FSRS signal and discuss contributions to sample degradation on the minute time scale. With these first successful proof-of-principle experiments, time-resolved SE-FSRS techniques can now be rationally attempted with the goals of investigating the dynamics of plasmonic materials as well as examining the contributions of environmental heterogeneities by probing more homogeneous molecular subsets.
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Affiliation(s)
- Renee R Frontiera
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Anne-Isabelle Henry
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Natalie L Gruenke
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Richard P Van Duyne
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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164
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Yakovlev VV, Noojin GD, Denton ML, Rockwell BA, Thomas RJ. Monitoring stimulated Raman scattering with photoacoustic detection. OPTICS LETTERS 2011; 36:1233-5. [PMID: 21479040 PMCID: PMC3095032 DOI: 10.1364/ol.36.001233] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A capability of high-frequency ultrasound detection to monitor the process of energy deposition into a molecular system via Raman excitation is experimentally demonstrated. It is shown that the generated ultrasound signal is directly proportional to the optical signal generated in stimulated Raman scattering. Ultrasound detection provides a simple way to discriminate against laser-induced breakdown and allows for the quantification of the stimulated Raman scattering process where direct optical detection is not available. Additionally, it can be used for stimulated Raman imaging in deep tissue, provided that the generated photoacoustic signal is sufficiently strong.
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Affiliation(s)
- Vladislav V Yakovlev
- Department of Physics, University of Wisconsin-Milwaukee, 1900 E. Kenwood Boulevard, Milwaukee, Wisconsin 53211, USA.
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165
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Pontecorvo E, Kapetanaki SM, Badioli M, Brida D, Marangoni M, Cerullo G, Scopigno T. Femtosecond stimulated Raman spectrometer in the 320-520nm range. OPTICS EXPRESS 2011; 19:1107-1112. [PMID: 21263650 DOI: 10.1364/oe.19.001107] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Multi-µJ narrow-bandwidth (≈ 10 cm(-1)) picosecond pulses, broadly tunable in the visible-UV range (320-520 nm), are generated by spectral compression of femtosecond pulses emitted by an amplified Ti:sapphire system. Such pulses provide the ideal Raman pump for broadband femtosecond stimulated Raman spectroscopy, as here demonstrated on a heme protein.
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Affiliation(s)
- E Pontecorvo
- Dipartimento di Fisica, Universitá Roma Sapienza, Roma, Italy
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166
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Park S, Kim J, Moran AM, Scherer NF. Solvent structural relaxation dynamics in dipolar solvation studied by resonant pump polarizability response spectroscopy. Phys Chem Chem Phys 2011; 13:214-23. [DOI: 10.1039/c0cp01252a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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167
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Kloz M, Grondelle RV, Kennis JT. Wavelength-modulated femtosecond stimulated raman spectroscopy—approach towards automatic data processing. Phys Chem Chem Phys 2011; 13:18123-33. [DOI: 10.1039/c1cp21650c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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168
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Dobryakov AL, Kovalenko SA, Weigel A, Pérez-Lustres JL, Lange J, Müller A, Ernsting NP. Femtosecond pump/supercontinuum-probe spectroscopy: optimized setup and signal analysis for single-shot spectral referencing. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:113106. [PMID: 21133460 DOI: 10.1063/1.3492897] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A setup for pump/supercontinuum-probe spectroscopy is described which (i) is optimized to cancel fluctuations of the probe light by single-shot referencing, and (ii) extends the probe range into the near-uv (1000-270 nm). Reflective optics allow 50 μm spot size in the sample and upon entry into two separate spectrographs. The correlation γ(same) between sample and reference readings of probe light level at every pixel exceeds 0.99, compared to γ(consec)<0.92 reported for consecutive referencing. Statistical analysis provides the confidence interval of the induced optical density, ΔOD. For demonstration we first examine a dye (Hoechst 33258) bound in the minor groove of double-stranded DNA. A weak 1.1 ps spectral oscillation in the fluorescence region, assigned to DNA breathing, is shown to be significant. A second example concerns the weak vibrational structure around t=0 which reflects stimulated Raman processes. With 1% fluctuations of probe power, baseline noise for a transient absorption spectrum becomes 25 μOD rms in 1 s at 1 kHz, allowing to record resonance Raman spectra of flavine adenine dinucleotide in the S(0) and S(1) state.
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Affiliation(s)
- A L Dobryakov
- Department of Chemistry, Humboldt University, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
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169
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Rhinehart JM, Mehlenbacher RD, McCamant D. Probing the Charge Transfer Reaction Coordinate of 4-(Dimethylamino)benzonitrile with Femtosecond Stimulated Raman Spectroscopy. J Phys Chem B 2010; 114:14646-56. [DOI: 10.1021/jp1023982] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Justin M. Rhinehart
- Department of Chemistry, University of Rochester, Rochester, New York 14627-0216
| | | | - David McCamant
- Department of Chemistry, University of Rochester, Rochester, New York 14627-0216
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170
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Chowdary PD, Benalcazar WA, Jiang Z, Marks DM, Boppart SA, Gruebele M. High speed nonlinear interferometric vibrational analysis of lipids by spectral decomposition. Anal Chem 2010; 82:3812-8. [PMID: 20373786 PMCID: PMC2869297 DOI: 10.1021/ac100222c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Unlike other CARS-based (coherent anti-Stokes Raman scattering) spectroscopy techniques, nonlinear interferometric vibrational spectroscopy (NIVS) is linear in analyte concentration and has a Raman line shape free of nonresonant background distortions. We use spontaneous Raman scattering as a high accuracy benchmark for NIVS. As a challenging comparison, we examine spectra in the CH stretching region of six lipid samples. Singular value decomposition and reference to an independent chemical assay are used to directly compare NIVS and spontaneous Raman scattering. We demonstrate that NIVS can determine the relative degree of unsaturation in six different lipid samples as accurately as spontaneous Raman spectroscopy, but 200 times faster. A skin tissue sample is mapped out to demonstrate quantitative lipid-protein differentiation with spatial resolution.
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Affiliation(s)
- Praveen D Chowdary
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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171
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Co DT, Lockard JV, McCamant DW, Wasielewski MR. Narrow-bandwidth tunable picosecond pulses in the visible produced by noncollinear optical parametric amplification with a chirped blue pump. APPLIED OPTICS 2010; 49:1880-1885. [PMID: 20357874 DOI: 10.1364/ao.49.001880] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Narrow-bandwidth (approximately 27 cm(-1)) tunable picosecond pulses from 480 nm-780 nm were generated from the output of a 1 kHz femtosecond titanium:sapphire laser system using a type I noncollinear optical parametric amplifier (NOPA) with chirped second-harmonic generation (SHG) pumping. Unlike a femtosecond NOPA, this system utilizes a broadband pump beam, the chirped 400 nm SHG of the Ti:sapphire fundamental, to amplify a monochromatic signal beam (spectrally-filtered output of a type II collinear OPA). Optimum geometric conditions for simultaneous phase- and group-velocity matching were calculated in the visible spectrum. This design is an efficient and simple method for generating tunable visible picosecond pulses that are synchronized to the femtosecond pulses.
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Affiliation(s)
- Dick T Co
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA
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172
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Niu K, Zhao B, Sun Z, Lee SY. Analysis of femtosecond stimulated Raman spectroscopy of excited-state evolution in bacteriorhodopsin. J Chem Phys 2010; 132:084510. [DOI: 10.1063/1.3330818] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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173
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Jailaubekov AE, Song SH, Vengris M, Cogdell RJ, Larsen DS. Using narrowband excitation to confirm that the S∗ state in carotenoids is not a vibrationally-excited ground state species. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.01.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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174
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Mapping GFP structure evolution during proton transfer with femtosecond Raman spectroscopy. Nature 2010; 462:200-4. [PMID: 19907490 DOI: 10.1038/nature08527] [Citation(s) in RCA: 336] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 09/09/2009] [Indexed: 11/08/2022]
Abstract
Tracing the transient atomic motions that lie at the heart of chemical reactions requires high-resolution multidimensional structural information on the timescale of molecular vibrations, which commonly range from 10 fs to 1 ps. For simple chemical systems, it has been possible to map out in considerable detail the reactive potential-energy surfaces describing atomic motions and resultant reaction dynamics, but such studies remain challenging for complex chemical and biological transformations. A case in point is the green fluorescent protein (GFP) from the jellyfish Aequorea victoria, which is a widely used gene expression marker owing to its efficient bioluminescence. This feature is known to arise from excited-state proton transfer (ESPT), yet the atomistic details of the process are still not fully understood. Here we show that femtosecond stimulated Raman spectroscopy provides sufficiently detailed and time-resolved vibrational spectra of the electronically excited chromophore of GFP to reveal skeletal motions involved in the proton transfer that produces the fluorescent form of the protein. In particular, we observe that the frequencies and intensities of two marker bands, the C-O and C = N stretching modes at opposite ends of the conjugated chromophore, oscillate out of phase with a period of 280 fs; we attribute these oscillations to impulsively excited low-frequency phenoxyl-ring motions, which optimize the geometry of the chromophore for ESPT. Our findings illustrate that femtosecond simulated Raman spectroscopy is a powerful approach to revealing the real-time nuclear dynamics that make up a multidimensional polyatomic reaction coordinate.
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175
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Mehlenbacher RD, Lyons B, Wilson KC, Du Y, McCamant DW. Theoretical analysis of anharmonic coupling and cascading Raman signals observed with femtosecond stimulated Raman spectroscopy. J Chem Phys 2009; 131:244512. [DOI: 10.1063/1.3276684] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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176
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Wilson KC, Lyons B, Mehlenbacher R, Sabatini R, McCamant DW. Two-dimensional femtosecond stimulated Raman spectroscopy: Observation of cascading Raman signals in acetonitrile. J Chem Phys 2009; 131:214502. [DOI: 10.1063/1.3263909] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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177
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Christensson N, Milota F, Nemeth A, Sperling J, Kauffmann HF, Pullerits T, Hauer J. Two-Dimensional Electronic Spectroscopy of β-Carotene. J Phys Chem B 2009; 113:16409-19. [DOI: 10.1021/jp906604j] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Niklas Christensson
- Department of Chemical Physics, Lund University, Box 124, SE-21000, Lund, Sweden, Department of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria, and Ultrafast Dynamics Group, Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria
| | - Franz Milota
- Department of Chemical Physics, Lund University, Box 124, SE-21000, Lund, Sweden, Department of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria, and Ultrafast Dynamics Group, Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria
| | - Alexandra Nemeth
- Department of Chemical Physics, Lund University, Box 124, SE-21000, Lund, Sweden, Department of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria, and Ultrafast Dynamics Group, Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria
| | - Jaroslaw Sperling
- Department of Chemical Physics, Lund University, Box 124, SE-21000, Lund, Sweden, Department of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria, and Ultrafast Dynamics Group, Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria
| | - Harald F. Kauffmann
- Department of Chemical Physics, Lund University, Box 124, SE-21000, Lund, Sweden, Department of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria, and Ultrafast Dynamics Group, Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria
| | - Tönu Pullerits
- Department of Chemical Physics, Lund University, Box 124, SE-21000, Lund, Sweden, Department of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria, and Ultrafast Dynamics Group, Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria
| | - Jürgen Hauer
- Department of Chemical Physics, Lund University, Box 124, SE-21000, Lund, Sweden, Department of Physical Chemistry, University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria, and Ultrafast Dynamics Group, Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria
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178
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Xie L, Ling X, Fang Y, Zhang J, Liu Z. Graphene as a substrate to suppress fluorescence in resonance Raman spectroscopy. J Am Chem Soc 2009; 131:9890-1. [PMID: 19572745 DOI: 10.1021/ja9037593] [Citation(s) in RCA: 252] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have measured resonance Raman spectra with greatly suppressed fluorescence (FL) background from rhodamine 6G (R6G) and protoporphyrin IX (PPP) adsorbed on graphene. The FL suppression is estimated to be approximately 10(3) times for R6G. The successful observation of resonance Raman peaks demonstrates that graphene can be used as a substrate to suppress FL in resonance Raman spectroscopy (RRS), which has potential applications in low-concentration detection and RRS study of fluorescent molecules.
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Affiliation(s)
- Liming Xie
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China
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179
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Niu K, Cong S, Lee SY. Femtosecond stimulated Raman scattering for polyatomics with harmonic potentials: application to rhodamine 6G. J Chem Phys 2009; 131:054311. [PMID: 19673566 DOI: 10.1063/1.3198473] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The perturbation theory of stimulated Raman scattering (SRS), with Raman pump on minus pump off and heterodyne detection along the probe direction, is reviewed. It has four third-order polarization terms, labeled as SRS or inverse Raman scattering (IRS): SRS(I), SRS(II), IRS(I), and IRS(II). These four polarizations have a wave packet interpretation. The polarizations, with homogenous and inhomogeneous broadening included, can be written as integrals over four-time correlation functions, and analytic formulas are derived for the latter for multidimensional harmonic potential surfaces with Franck-Condon displacements in the modes which facilitates the calculation of the SRS cross sections. The theory is applied to understand recent experimental results on the femtosecond SRS (FSRS) of a fluorescent dye, rhodamine 6G (R6G), where the Raman pump pulse is about 1 ps long, and the probe pulse is about 10 fs. The calculations compared very well with the R6G experimental results for off-resonance and resonance FSRS spectra spanning both Stokes and anti-Stokes bands, and for negative and positive pump-probe delay times on resonance.
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Affiliation(s)
- Kai Niu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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180
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Frontiera RR, Dasgupta J, Mathies RA. Probing Interfacial Electron Transfer in Coumarin 343 Sensitized TiO2 Nanoparticles with Femtosecond Stimulated Raman. J Am Chem Soc 2009; 131:15630-2. [PMID: 19860478 DOI: 10.1021/ja907188b] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Renee R. Frontiera
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Jyotishman Dasgupta
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Richard A. Mathies
- Department of Chemistry, University of California, Berkeley, California 94720
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181
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Spillane KM, Dasgupta J, Lagarias JC, Mathies RA. Homogeneity of phytochrome Cph1 vibronic absorption revealed by resonance Raman intensity analysis. J Am Chem Soc 2009; 131:13946-8. [PMID: 19739629 PMCID: PMC2880177 DOI: 10.1021/ja905822m] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phytochromes are an important class of red/far-red responsive photoreceptors that act as light-activated biological switches, ultimately driving growth and development in plants, bacteria, and fungi. The composition of the red-absorbing ground-state has been widely debated due to the presence of a shoulder feature on the blue edge of electronic absorption spectra, which many have attributed to the presence of multiple ground-state conformers. Here we use resonance Raman intensity analysis to calculate the vibronic absorption profile of cyanobacterial phytochrome Cph1 and show that this shoulder feature is due simply to vibronic transitions from a single species, thus reflecting a homogeneous ground-state population.
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Affiliation(s)
- Katelyn M. Spillane
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Jyotishman Dasgupta
- Department of Chemistry, University of California, Berkeley, California 94720
| | - J. Clark Lagarias
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - Richard A. Mathies
- Department of Chemistry, University of California, Berkeley, California 94720
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182
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Siebert R, Akimov D, Schmitt M, Winter A, Schubert US, Dietzek B, Popp J. Spectroscopic investigation of the ultrafast photoinduced dynamics in pi-conjugated terpyridines. Chemphyschem 2009; 10:910-9. [PMID: 19301307 DOI: 10.1002/cphc.200800847] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ultrafast light-induced processes in a series of pi-conjugated mono-, bis-, tris- and tetrakis(terpyridine) derivatives are investigated by femtosecond time-resolved spectroscopy. Non-exponential excited-state dynamics involving singlet-triplet intersystem crossing are observed which span from picoseconds to nanoseconds (see figure). Time-resolved spectroscopy is applied to investigate the ultrafast relaxation dynamics of several pi-conjugated mono-, bis-, tris- and tetrakis(terpyridine) derivatives. This particular series of structurally closely related systems was prepared applying efficient synthetic strategies and resembles key building blocks for a wide range of photoactive complexes, dendrimers and metallo-polymers with resulting potential applications, for example, in photovoltaics or as organic light-emitting diodes. Aiming for applications of supramolecular assemblies based on these recently presented terpyridine ligands a detailed knowledge of the light-induced processes of the ligands themselves represents a prerequisite. By applying femtosecond time-resolved absorption spectroscopy in concert with time-resolved fluorescence and Raman measurements, we detail the photophysical properties.
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Affiliation(s)
- Ronald Siebert
- Institute for Physical Chemistry, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany
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183
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Shim S, Dasgupta J, Mathies RA. Femtosecond Time-Resolved Stimulated Raman Reveals the Birth of Bacteriorhodopsin’s J and K Intermediates. J Am Chem Soc 2009; 131:7592-7. [DOI: 10.1021/ja809137x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sangdeok Shim
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Jyotishman Dasgupta
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Richard A. Mathies
- Department of Chemistry, University of California, Berkeley, California 94720
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184
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Marangoni M, Brida D, Conforti M, Capobianco AD, Manzoni C, Baronio F, Nalesso GF, De Angelis C, Ramponi R, Cerullo G. Synthesis of picosecond pulses by spectral compression and shaping of femtosecond pulses in engineered quadratic nonlinear media. OPTICS LETTERS 2009; 34:241-3. [PMID: 19183618 DOI: 10.1364/ol.34.000241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Narrow-bandwidth picosecond pulses of predetermined spectral and temporal shapes are generated with high efficiency by frequency conversion of femtosecond pulses in lithium tantalate crystals with engineered quasi-phase-matching structures. We give examples of the synthesis of Gaussian and super-Gaussian picosecond pulses and also of a pair of synchronized phase-coherent picosecond pulses with a predetermined carrier-frequency difference.
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Affiliation(s)
- M Marangoni
- Dipartimento di Fisica-Politecnico di Milano, ULTRAS Istituto Nazionale per la Fisica delle Materia-Consiglio Nazionale delle Ricerche, Milano, Italy.
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185
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Ultrafast excited-state isomerization in phytochrome revealed by femtosecond stimulated Raman spectroscopy. Proc Natl Acad Sci U S A 2009; 106:1784-9. [PMID: 19179399 DOI: 10.1073/pnas.0812056106] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Photochemical interconversion between the red-absorbing (P(r)) and the far-red-absorbing (P(fr)) forms of the photosensory protein phytochrome initiates signal transduction in bacteria and higher plants. The P(r)-to-P(fr) transition commences with a rapid Z-to-E photoisomerization at the C(15)=C(16) methine bridge of the bilin prosthetic group. Here, we use femtosecond stimulated Raman spectroscopy to probe the structural changes of the phycocyanobilin chromophore within phytochrome Cph1 on the ultrafast time scale. The enhanced intensity of the C(15)-H hydrogen out-of-plane (HOOP) mode, together with the appearance of red-shifted C=C stretch and N-H in-plane rocking modes within 500 fs, reveal that initial distortion of the C(15)=C(16) bond occurs in the electronically excited I* intermediate. From I*, 85% of the excited population relaxes back to P(r) in 3 ps, whereas the rest goes on to the Lumi-R photoproduct consistent with the 15% photochemical quantum yield. The C(15)-H HOOP and skeletal modes evolve to a Lumi-R-like pattern after 3 ps, thereby indicating that the C(15)=C(16) Z-to-E isomerization occurs on the excited-state surface.
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186
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Sun Z, Fu B, Zhang DH, Lee SY. Theoretical investigation of the direct observation of anharmonic coupling in CDCl3 in the time domain with femtosecond stimulated Raman scattering. J Chem Phys 2009; 130:044312. [DOI: 10.1063/1.3068709] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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187
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Frontiera RR, Shim S, Mathies RA. Origin of negative and dispersive features in anti-Stokes and resonance femtosecond stimulated Raman spectroscopy. J Chem Phys 2008; 129:064507. [PMID: 18715085 DOI: 10.1063/1.2966361] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Femtosecond stimulated Raman spectroscopy is extended to probe ground state anti-Stokes vibrational features. Off resonance, negative anti-Stokes features are seen that are the mirror image of the positive Stokes side spectra. On resonance, the observed dispersive lineshapes are dramatically dependent on the frequencies of the picosecond pump and femtosecond probe pulses used to generate the stimulated Raman spectra. These observations are explained by the contributions of the inverse Raman and hot luminescence four-wave mixing processes discussed by Sun et al. [J. Chem. Phys. 128, 144114 (2008)], which contribute to the overall femtosecond stimulated Raman signal.
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Affiliation(s)
- Renee R Frontiera
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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188
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Gruetzmacher JA, Nome RA, Moran AM, Scherer NF. Assessing the dephasing dynamics of water from linear field-resolved pulse propagation experiments and simulations in highly absorbing solutions. J Chem Phys 2008; 129:224502. [DOI: 10.1063/1.2990654] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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189
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Slipchenko MN, Prince BD, Ducatman SC, Stauffer HU. Development of a Simultaneously Frequency- and Time-Resolved Raman-Induced Kerr Effect Probe. J Phys Chem A 2008; 113:135-40. [DOI: 10.1021/jp804283s] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
| | | | | | - Hans U. Stauffer
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111
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190
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Guthmuller J, Champagne B. Resonance Raman Spectra and Raman Excitation Profiles of Rhodamine 6G from Time-Dependent Density Functional Theory. Chemphyschem 2008; 9:1667-9. [DOI: 10.1002/cphc.200800253] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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191
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Sun Z, Lu J, Zhang DH, Lee SY. Quantum theory of (femtosecond) time-resolved stimulated Raman scattering. J Chem Phys 2008; 128:144114. [PMID: 18412430 DOI: 10.1063/1.2888551] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a complete perturbation theory of stimulated Raman scattering (SRS), which includes the new experimental technique of femtosecond stimulated Raman scattering (FSRS), where a picosecond Raman pump pulse and a femtosecond probe pulse simultaneously act on a stationary or nonstationary vibrational state. It is shown that eight terms in perturbation theory are required to account for SRS, with observation along the probe pulse direction, and they can be grouped into four nonlinear processes which are labeled as stimulated Raman scattering or inverse Raman scattering (IRS): SRS(I), SRS(II), IRS(I), and IRS(II). Previous FSRS theories have used only the SRS(I) process or only the "resonance Raman scattering" term in SRS(I). Each process can be represented by an overlap between a wave packet in the initial electronic state and a wave packet in the excited Raman electronic state. Calculations were performed with Gaussian Raman pump and probe pulses on displaced harmonic potentials to illustrate various features of FSRS, such as high time and frequency resolution; Raman gain for the Stokes line, Raman loss for the anti-Stokes line, and absence of the Rayleigh line in off-resonance FSRS from a stationary or decaying v=0 state; dispersive line shapes in resonance FSRS; and the possibility of observing vibrational wave packet motion with off-resonance FSRS.
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Affiliation(s)
- Zhigang Sun
- Division of Physics & Applied Physics, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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192
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Shim S, Stuart CM, Mathies RA. Resonance Raman cross-sections and vibronic analysis of rhodamine 6G from broadband stimulated Raman spectroscopy. Chemphyschem 2008; 9:697-9. [PMID: 18330856 DOI: 10.1002/cphc.200700856] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sangdeok Shim
- Department of Chemistry, University of California, Berkeley, CA 94720, United States
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193
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Shim S, Mathies RA. Development of a Tunable Femtosecond Stimulated Raman Apparatus and Its Application to β-Carotene. J Phys Chem B 2008; 112:4826-32. [DOI: 10.1021/jp710518y] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sangdeok Shim
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Richard A. Mathies
- Department of Chemistry, University of California, Berkeley, California 94720
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194
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Moran AM, Nome RA, Scherer NF. Field-resolved measurement of reaction-induced spectral densities by polarizability response spectroscopy. J Chem Phys 2007; 127:184505. [DOI: 10.1063/1.2792943] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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195
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Frontiera RR, Mathies RA. Polarization dependence of vibrational coupling signals in femtosecond stimulated Raman spectroscopy. J Chem Phys 2007; 127:124501. [PMID: 17902915 DOI: 10.1063/1.2780843] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The polarization dependence of vibrational coupling signals seen in femtosecond stimulated Raman spectroscopy (FSRS) is investigated. Changing the polarization of a pulse used to impulsively excite coherent low frequency chlorine bending motion in CDCl(3) has a dramatic effect on the line shape of vibrational sidebands which arise from the anharmonic coupling of the pumped modes at 262 and 365 cm(-1) with the higher frequency symmetric stretching mode at 652 cm(-1). The asymmetric bend sideband (652+262 cm(-1)) changes sign and magnitude as the impulsive pulse polarization is rotated relative to the Raman pulses, while the symmetric bend sideband (652+365 cm(-1)) is relatively polarization independent. These experiments demonstrate the ability of FSRS to obtain time-resolved information on not only the vibrational coupling strength but also the symmetry of anharmonically coupled modes.
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Affiliation(s)
- Renee R Frontiera
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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196
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Moran AM, Park S, Scherer NF. Polarizability response spectroscopy: Formalism and simulation of ultrafast dynamics in solvation. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.09.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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197
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198
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Urbanek DC, Berg MA. Simultaneous time and frequency detection in femtosecond coherent Raman spectroscopy. I. Theory and model calculations. J Chem Phys 2007; 127:044306. [PMID: 17672689 DOI: 10.1063/1.2752165] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
For coherent Raman spectroscopies, common femtosecond pulses often lie in an intermediate regime: their bandwidth is too wide for measurements in the frequency domain, but their temporal width is too broad for homodyne measurements in the time domain. A recent paper [S. Nath et al., Phys. Rev. Lett. 97, 267401 (2006)] showed that complete Raman spectra can be recovered from intermediate length pulses by using simultaneous time and frequency detection (TFD). Heterodyne detection and a phase-stable local oscillator at the anti-Stokes frequency are not needed with TFD. This paper examines the theory of TFD Raman in more detail; a companion paper tests the results on experimental data. Model calculations illustrate how information on the Raman spectrum is transferred from the frequency domain to the time domain as the pulse width shortens. When data are collected in both dimensions, the Raman spectrum is completely determined to high resolution, regardless of the probe pulse width. The loss of resolution in many femtosecond coherent Raman experiments is due to the restriction to one-dimensional data collection, rather than due to a fundamental restriction based on the pulse width.
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Affiliation(s)
- Diana C Urbanek
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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199
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Nath S, Urbanek DC, Kern SJ, Berg MA. Simultaneous time and frequency detection in femtosecond coherent Raman spectroscopy. II. Application to acetonitrile. J Chem Phys 2007; 127:044307. [PMID: 17672690 DOI: 10.1063/1.2752166] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The preceding paper showed that, in principle, a high-resolution coherent Raman spectrum can be recovered using femtosecond probe pulses by combined detection in both time and frequency. This measurement is possible even when the pulses are too broad in frequency for conventional frequency-domain spectroscopy and too broad in time for conventional time-domain spectroscopy. In this paper, the method is tested on experimental coherent anti-stokes Raman spectroscopy data from acetonitrile. Compared to theoretical models, experimental data are complicated by noise and incomplete knowledge of the pulse structure. Despite these complications, most of the information in the Raman spectrum is recovered from the data: weak transitions are detected and natural-linewidth resolution is achieved across an 800 cm(-1) spectral range. However, circumstances in which experimental limitations result in missed features or ambiguities in the recovered spectrum are also identified. These results suggest where improvements in measurement and data analysis can be made.
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Affiliation(s)
- Sukhendu Nath
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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200
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Conforti M, Baronio F, De Angelis C. From femtosecond infrared to picosecond visible pulses: temporal shaping with high-efficiency conversion. OPTICS LETTERS 2007; 32:1779-81. [PMID: 17603567 DOI: 10.1364/ol.32.001779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present a single-pass frequency doubler that efficiently converts broadband near-infrared femtosecond pulses into narrow-spectrum visible picosecond pulses. An optimal control technique is introduced for properly designing aperiodically poled nonlinear crystals to generate visible pulses of the desired amplitude, phase profile, and carrier wavelength.
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Affiliation(s)
- Matteo Conforti
- Dipartimento di Elettronica per l'Automazione, Università di Brescia, via Branze 38, 25123 Brescia, Italy.
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