English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The vibrational relaxation mechanism of CH 3 F whose   ν   3  mode is excited by a transverselyexcited atmospheric (TEA)CO 2  laser-pulse has been discussed on the basis ofobservation of the laser-induced fluorescence (LIF) of the   ν   3  overtones and of the C–Hstretching modes and kinetic analyses. The time-evolved LIF in the 3-μm region wasfound to be dependent significantly on the laser fluence; at a low fluence (&lt;0.01 J cm −2 ),the emission intensity increased almost exponentially with a rate similar to the onedetermined in the experiment with a Q-switched laser, while at a higher fluence(&gt;0.1 J cm −2 ) the emission rose much faster to form a peak which decayed quicklybefore a second broad peak appeared. In the wavelength-resolved fluorescencemeasurement, it was found that the kinetics of population in the   ν   4  level were similar tothose in the 3  ν   3  level, while those in the   ν   1 , 2  ν   5 ,   ν   2  +   ν   5  and 2  ν   2  levels behaved in a waydifferent from those in the   ν   4  level. These observations lead to the conclusion that thelaser energy poured into the   ν   3  mode flows to the   ν   4  level directly through 3  ν   3  as well asby the successive inter- and intramode V–V energy transfers, i.e.,   ν   3 →  ν   6 →  ν   2 ,   ν   5 →2(  ν   2 ,   ν   5 )→  ν   1 →  ν   4 . A model calculation of the relaxation kinetics, including thedirect V–V energy transfer between two 3  ν   3  and   ν   4  levels, could reproduce the 3-μmemission data. Another significant finding is a non-exponential depopulation in the 2  ν   3 level, the   ν   4 ,   ν   1  and other vibrational levels in the 3-μm region in the final stage of therelaxation. The deactivation rate is larger for a higher level and is a decreasing functionof time and is much larger than the V–T/R energy transfer rate. determined in the experiment of weak laser excitation. This may be attributed primarily to the successiveintermode V–V energy transfers from the 3  ν   3  to the   ν   4 ,   ν   1 , 2  ν   5 , . . . levels which liebetween the 2  ν   3  and 3  ν   3  levels. This process may be repeated if the intramode V–Venergy transfer from the 2  ν   3  to the 3  ν   3  level occurs. The deactivation mechanism foundin this experiment is called ‘catastrophic cyclic path’ which is effective until the relativepopulation distribution in relevant levels between 2  ν   3  and 3  ν   3  becomes that in equilibriumat the translational temperature of the CH 3 F gas.

Intra- and Intermode Vibrational Energy Flow in CH3F Excited by Irradiation With an Intense CO2 Laser: A Non-Linear Vibrational Relaxation