Transient vibrational echo versus transient absorption spectroscopy: a direct experimental and theoretical comparison.
Transient dispersed vibrational echo (DVE) spectroscopy is a practical alternative to transient-absorption spectroscopy because it affords increased sensitivity as well as greater signal-to-noise ratio without the need to detect a reference spectrum. However, as a third-order nonlinear probe, the extraction of kinetic information from transient-DVE is somewhat cumbersome compared to transient absorption. This article provides a direct experimental and theoretical comparison between transient-absorption and transient-DVE measurements and presents a framework for analyzing kinetic measurements while exploring the implications of making some simplifying assumptions in the data analysis. The equations for computing the signal-to-noise ratios under different experimental conditions are derived and used in the analysis of the experimental data. The results, obtained under the same experimental conditions, show that for a relatively strong terminal carbonyl stretching mode, signal-to-noise ratios in transient-DVE spectroscopy are approximately 2.5 times greater than transient absorption. The experimental results along with the theoretical models indicate that transient-DVE could become an attractive alternative to transient-absorption spectroscopy for measuring the kinetics of light-induced processes.
Baiz
Carlos R
CR
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
McCanne
Robert
R
Kubarych
Kevin J
KJ
D000042:Absorption; D000465:Algorithms; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D013055:Spectrophotometry, Infrared / Q000379:methods*; D014732:Vibration