Short-time photodissociation dynamics of iodoalkanes: refinement using resonance Raman intensities of isotopic derivatives

✍ Scribed by David Lee Phillips; Anne B. Myers

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 447 KB
• Volume: 28
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199711)28:11<839::aid-jrs166>3.0.co;2-1

✦ Synopsis

Resonance Raman spectra of and iodide in cyclohexane solution were 1,1,1,3,3,3-d 6 -2-iodopropane d 9 -tert-butyl obtained at excitation wavelengths of 266 and 217.8 nm. The 266 nm spectra, resonant with the directly dissociative A-state absorption, display long overtone progressions in the nominal C-I stretch (ca. 500 cm-1) and some intensity in fundamentals, overtones and combination bands of bending and C-C stretching modes. The 266 nm resonance Raman intensities and the A-band absorption spectrum are simultaneously modelled using wavepacket propagation on a multidimensional locally harmonic potential surface. The dimensionless normal coordinate wavepacket motions determined from the simulations are converted into internal coordinate motions by making use of previous results on the isotopically unsubstituted compounds to remove some of the indeterminacy in the signs of the normal mode displacements. In the Ðrst 10 fs the CÈI bond lengthens less in these higher alkanes than in iodoethane, suggesting that more of the available energy goes toward CÈI bond cleavage in iodoethane. 1997