Vibration-rotation tunneling spectra

Elrod, M. J., and Saykally, R. J., Determination of the intermolecular potential energy surface for (HClj from vibration-rotation-tunneling spectra, J. Chem. Phys. 103,933-949 (1995). Latajka, Z., and Scheiner, S., Structure, energetics and vibrational spectra ofH-bonded systems. Dimers and trimers ofHFand HCl, Chem. Phys. 122, 413 30 (1988). 

Saykally, Determination of the intermolecular potential energy surface for (HC1)2 from vibration-rotation-tunneling spectra, J. Chem. Phys., 103 1995) 933-949. 

Liu K, Brown M G, Cruzan J D and Saykally R J 1996 Vibration-rotation tunnelling spectra of the water pentamer Science 271 62-4... 

Liu, K., Brown, M. G., Cruzan, J. D., Saykally, R. J. (1996a). Vibration-rotation tunneling spectra of the water pentamer Structure and dynamics. Science, 271, 62-64. 

The tetramer is also cyclic ", as illustrated in Fig. 5.24, and with a greater degree of symmetry than the trimer, belonging to the point group. The ring is sequential in the sense that each molecule acts as simultaneous donor and acceptor. This type of structure has been confirmed by analysis of the far-IR vibration-rotation tunneling spectrum . The correlated R(O- O) distances are all equal to 2.743 A, about 0.06 A shorter than in the trimer. (The ex-... 

Olthof, E. H. T., van der Avoird, A, and Wormer, R E. S., Structure, internal mobility, and spectrum of the ammonia dimer Calculation of the vibration-rotation tunneling states, J. Chem. Phys. 101, 8430-8442 (1994). 

In case of the related complex (HCl) comparatively few accurate spectroscopic investigations have been performed to date. Very recently, Blake et al. 713/ reported a far infrared rotation-tunnelling spectrum. In a related investigation Moazzen-Ahmadi et al. 714/ analyzed the torsional vibration of (HC1)2 Fundamental frequencies of the... 

Dissociation occurring by tunneling from a bound to an unbound rovibronic state (i.e., a state corresponding to a particular rotational energy level of a vibrational level of an electronic state). 2. The appearance of a diffuse band region within a series of sharp bands of an absorption spectrum. 

We now consider hydrogen transfer reactions between the excited impurity molecules and the neighboring host molecules in crystals. Prass et al. [1988, 1989] and Steidl et al. [1988] studied the abstraction of an hydrogen atom from fluorene by an impurity acridine molecule in its lowest triplet state. The fluorene molecule is oriented in a favorable position for the transfer (Figure 6.18). The radical pair thus formed is deactivated by the reverse transition. H atom abstraction by acridine molecules competes with the radiative deactivation (phosphorescence) of the 3T state, and the temperature dependence of transfer rate constant is inferred from the kinetic measurements in the range 33-143 K. Below 72 K, k(T) is described by Eq. (2.30) with n = 1, while at T>70K the Arrhenius law holds with the apparent activation energy of 0.33 kcal/mol (120 cm-1). The value of a corresponds to the thermal excitation of the symmetric vibration that is observed in the Raman spectrum of the host crystal. The shift in its frequency after deuteration shows that this is a libration i.e., the tunneling is enhanced by hindered molecular rotation in crystal. 

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