Rotational-vibrational energy transfer

Recently this idea has received much attention in the chemical physics community, brought about by accurate measurements [20-22] of rotational-vibrational energy transfer in collisions of H with H2. Kuppermann [23-26]... 

In this overview of recent calculations that we have performed on polyatomic rotational-vibrational energy transfer and predissociation we have attempted to illustrate the many types of calculations and systems that can now be studied using quite rigorous quantum... 

H. C. Hung, Rotational-vibrational energy transfer. Dynamics of a rotating anharmonic four-atom molecule, J. Chem. Phys. 57 ... 

E. Vilallonga, D. A. Micha, and J. P. Toennies, Rotational-vibrational energy transfer in atom-polyatomic collisions Li -C02 in the 1 to 10 eV range, Chem. Phys. Lett. 68 352 (1979). 

Kreutz T G and Flynn G W 1990 Analysis of translational, rotational, and vibrational energy transfer in collisions between COj and hot hydrogen atoms the three dimensional breathing ellipse model J. Chem. Phys. 93 452-65... 

Fig. 9. Incidence energy dependence of the vibrational state population distribution resulting when NO(u = 12) is scattered from LiF(OOl) at a surface temperature of (a) 480 K, and (b) 290 K. Relaxation of large amplitude vibrational motion to phonons is weak compared to what is possible on metals. Increased relaxation at the lowest incidence energies and surface temperatures are indicators of a trapping/desorption mechanism for vibrational energy transfer. Angular and rotational population distributions support this conclusion. Estimations of the residence times suggest that coupling to phonons is significant when residence times are only as long as ps. (See Ref. 58.)...

Relaxation processes e. g. rotational isomerisation or vibrational energy transfer. 

Investigations of vibrational energy transfer and its dependece on temperature, rotational state distribution, energy defect and other parameters, therefore, have been one of the main research subjects 413)-415)... 

In the pure impulsive model, the total excess energy Eexcess partitions into translational energy of both products, as well as vibrational and rotational energy of the diatomic fragment. In a modified version, Busch and Wilson (1972a) assumed that the B-C bond is infinitely stiff such that vibrational energy transfer is prohibited. Employing conservation of... 

Vibrational (V) to Rotational (R) Energy Transfer Hydrogen Fluoride Dimer... 

If the OH undergoes rotational energy transfer, it will undergo vibrational energy transfer as well (22). Figure 5 shows the emission from the v7=l level following excitation of the N7 =4 rotational level in v/=0. This results from molecules which have been collisionally transferred upwards some 3000 cm"l. Also shown in Fig. 5, on the same intensity scale, is a small portion of the emission from v7=0. From a ratio of these intensities, we find that the v/=l population is about 3.5% of that in v7 0, N. ... 

The important conclusions of these studies are that, even at low pressures, collisions can drastically modify fluorescence decay curves. Rotational and/or vibrational energy transfer can stabilize an initially formed predissociated state by downward relaxation and conversely can destabilize a stable state by upward energy transfer into an unstable part of the energy level manifold. 

An aspect of 12(A) collisional energy transfer that complicated the data analysis is apparent in Fig. 4. While it was obvious that rotational energy transfer was much faster than vibrational transfer (e.g. compare the intensities of the t = 23 and t = 22 rotational lines in Fig. 4), vibrational energy transfer was fast enough to be detectable well before rotational thermaliza-tion of the initially excited vibrational level had been achieved (with the exception of I2-I2 collisions). Therefore, in constructing kinetic models of the relaxation processes, rotational and vibrational energy transfer could... 

COFj has found favour as a target molecule in energy transfer studies as its vibrational energy transfer processes are relatively little affected by rotational complications, its ir vibrational modes are all allowed and its constituent atoms are all of comparable large mass - a feature that means the vibrational modes are all easily accessible to one laser. 

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