Related Experiment Video
Updated: Jun 16, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Time-resolved molecular excitation and heat effects induced by infrared radiation
Abstract:
A saturable absorber (SF(6)) is irradiated by a step of radiation from a CO(2) laser, and the step response of the medium is observed. Since the characteristic times of rotational, vibrational, and thermal excitation are different, it is possible to observe each process separately. A set of rate equations is developed for a simplified model of two energy levels. This set includes only one differential equation and qualitatively describes the effects of rotational hole burning and vibrational relaxation. Heat effects are accounted for separately.
Related Concept Videos
Infrared (IR) Spectroscopy: Overview
Different compounds display unique properties due to their...
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Atomic Spectroscopy: Effects of Temperature
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
Molecular Spectroscopy: Absorption and Emission
IR Spectrum
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0% (complete...
Mechanisms of Heat Transfer II

