The time-resolved femtosecond stimulated Raman spectra (FSRS) of a charge transfer (CT) excited noncovalent complex tetracyanoethylene:1-chloronaphthalene (TCNE:ClN) in dichloromethane (DCM) is reported with 40 fs time resolution. In the frequency domain, five FSRS peaks are observed with frequencies of 534, 858, 1069, 1392, and 1926 cm. The most intense peaks at 534 and 1392 cm correspond to fundamentals while the features at 858, 1069, and 1926 cm are attributed to a difference frequency, an overtone and a combination frequency of the fundamentals, respectively. The frequency of the 1392 cm fundamental corresponding to the central C═C stretch of TCNE is red-shifted from the frequency of the steady state radical due to the close proximity and electron affinity of the countercation. The observation of a FSRS band at a difference frequency is analyzed. This analysis lends evidence for alternative nonlinear pathways of inverse Raman gain scattering (IRGS) or vertical-FSRS (VFSRS) which may contribute to the time-evolving FSRS spectrum on-resonance. Impulsive stimulated Raman measurements of the complex show coherent oscillations of the stimulated emission with frequencies of 153, 278, and 534 cm. The 278 cm mode corresponds to Cl bending of the dichloromethane solvent. The center frequency of the 278 cm mode is modulated by a frequency of ∼30 cm which is attributed to the effect of librational motion of the dichloromethane solvent as it reorganizes around the nascent contact ion pair. The 153 ± 15 cm mode corresponds to an out-of-plane bending motion of TCNE. This motion modulates the intermolecular separation of the contact ion pair and thereby the overlap of the frontier orbitals which is crucial for rapid charge recombination in 5.9 ± 0.2 ps. High time-frequency resolution vibrational spectra provide unique molecular details regarding charge localization and recombination.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/acs.jpca.8b00318 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Label-free nanoscopy of cell metabolism by ultrasensitive reweighted visible stimulated Raman scattering.
Nat Methods
January 2025
Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA.
Super-resolution imaging of cell metabolism is hindered by the incompatibility of small metabolites with fluorescent dyes and the limited resolution of imaging mass spectrometry. We present ultrasensitive reweighted visible stimulated Raman scattering (URV-SRS), a label-free vibrational imaging technique for multiplexed nanoscopy of intracellular metabolites. We developed a visible SRS microscope with extensive pulse chirping to improve the detection limit to ~4,000 molecules and introduced a self-supervised multi-agent denoiser to suppress non-independent noise in SRS by over 7.
View Article and Find Full Text PDFIn this study, we investigated in detail the regulation mechanism of electron transfer under laser-induced breakdown (LIB) on weak O-D stimulated Raman scattering (SRS) in DMSO-DO solutions. Significantly, the Raman activity of O-D vibrations was greatly enhanced by two orders of magnitude due to electron transfer in DMSO molecules. Density functional theory (DFT) calculations showed that the O-D Raman activity was significantly enhanced in the DMSO-DO dimer compared to the DO dimer.
View Article and Find Full Text PDFWe introduce and characterize a fast (50 kHz), long range (50 ps) and random-access optical delay line based on an acousto-optic deflector inserted in the Fourier plane of a zero-dispersion line. The advantages of this agile delay line are demonstrated in the context of impulsive stimulated Raman imaging in the low-frequency range (<200 cm). Besides fast imaging with a spectral resolution of 1.
View Article and Find Full Text PDFThis publisher's note contains a correction to Opt. Lett.49, 4863 (2024)10.
View Article and Find Full Text PDFSmart and Noninvasive SERS Immunosensors for Monitoring Dynamic Expression of Cytokines during Cell Pyroptosis.
Anal Chem
January 2025
Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen 518060, PR China.
Accompanying the occurrence of inflammatory reaction to release cytokines, pyroptosis can activate an immune response for resistance against cancer. Consequently, elevated levels of cytokines released by cancer cells are highly correlated with the effectiveness of cancer treatment. Herein, a noninvasive surface-enhanced Raman spectroscopy (SERS) immunosensor was developed to sensitively and specifically measure the tumor necrosis factor-α (TNF-α), a proinflammatory cytokine, during the cell pyroptosis process.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!