ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We predict a new quantum isotope effect for unimolecular dissociations of molecules with two equivalent but isotopically substituted bonds l (light isotope) and h (heavy isotope), e.g., HOT where l=HO and h=OT. Consider two near-degenerate local vibrational excitations of bonds l or h, with energies between the gap of product zero point energies. Dynamically, these excitations should induce preferential fissions of bonds l or h, but energetically, these decay channels are open and closed, respectively. Therefore, local excitation of bond h must be followed by extremely slow internal vibrational energy redistribution to bond l before dissociation, whereas local excitation of bond l induces direct, rapid decay. The resulting decay rates differ by many orders of magnitudes. The effect is demonstrated by fast Fourier transform propagation of representative wavepackets for a model system, HOT→H+OT. Extended applications to more excited educts HOT also confirm an effect discovered previously for HOD, i.e., local mode selective control of competing bond fissions H+OT←HOT→HO+T.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.458466
