Investigation of sulfur-containing compound molecular dynamics using the analytical methods of two-dimensional infrared, FTIR and FT-Raman spectroscopy.

摘要

Understanding molecular properties and their responses to changes in environmental conditions is an important challenge in modern science. Molecular responses provide insight into the dynamics of many systems found in our everyday world. Yet the timescales of measurable dynamics are limited by the resolution of the measurement system. For accessing faster dynamics, time-resolved techniques are necessary. Transient absorption spectroscopy involves the spectra of the sample as a function of the time delay after a triggered flash. Spectral changes associated with the formation of varied excited states and products of reactions occurring in the excited states can be recorded.;The improvement of technological development in optical devices over time has led to a new class of spectroscopic instrumentation and techniques for probing vibrational transitions, such as linear FTIR, Raman, and 2DIR spectroscopy. The vibrational frequency of atomic bonds in molecule can provide structural information such as bond order, which correlates to the bond distance between two atoms. A change in the frequency of a molecular bond may be directly correlated to a change in its environment. In 2DIR spectroscopy, for structures in large molecules that feature congested and complex IR spectra, such as for example proteins, it is essential to introduce new vibrational reporters and explore new spectral regions. Because of a polar character of the sulfoxide (SO) group, the S=O stretching modes in sulfoxides are sensitive to the local environment as well as to the redox state of the compound. The molecular spectra in the fingerprint region (800 -- 1500 cm-1) are known to be congested, difficult in interpreting, and at the same time very characteristic for the molecule. We investigate the fingerprint region to access a spectral region which is not widely studied due to its complexity with the techniques of linear IR, pump-probe IR, dual-frequency 2DIR, and relaxation-assisted 2DIR spectroscopy, we explore the fingerprint region and the use of the sulfoxide mode to characterize molecular dynamics to promote the fingerprint region as an important facet of molecular dynamics information.