Intermolecular V–V energy transfer in the photodissociation of CO2–HF(v=1)

Asymmetry in angular rigidity of hydrogen-bonded complexes

The asymmetry in angular rigidity of the proton donor and proton acceptor of hydrogen-bonded hydrogen fluoride binary complexes is investigated. The intermolecular bending frequency of HF, as the proton donor, is linearly proportional to the square root of the dissociation energy, whereas that of the proton acceptor is always much lower. The asymmetry, measured by the ratio of bending elastic constants of HF to that of the proton acceptor, is generally >2, and varies pronouncedly with the acceptors reaching values >20. Molecules with nitrogen as the bridged acceptor atom show an angular rigidity nearly one order of magnitude greater than the group with oxygen as the proton acceptor.

Pendular-state spectroscopy of the S1–S0 electronic transition of 9-cyanoanthracene

Fluorescence excitation spectra of the S(1)-S(0) origin band of 9-cyanoanthracene have been observed under a uniform electric field up to 200 kV/cm to explore pendular-state spectrum of an asymmetric-top molecule close to the strong field limit. The observed spectra exhibit distinct evolution of the band contour as a function of the applied electric field, which are much different from each other for different excitation configurations. An approximate method suitable for spectrum simulations of large asymmetric-top molecules in a pendular condition is developed for the analysis of the experimental results. The comparison of the observed and simulated spectra shows that the spectra are well ascribed in terms of the pendular-state selection rules, which have recently been derived from theoretical consideration of the pendular-limit representation of energy levels and spectra.

Photofragment translational spectroscopy of weakly bound complexes: probing the interfragment correlated final state distributions

The vibrational predissociation dynamics of weakly bound complexes is well known to be highly nonstatistical. In particular, the associated photofragment final state distributions are often far from statistical, consequently reflecting the nature of the dissociation process. For binary complexes consisting of two molecules, a complete description of the final state of the system must include the associated interfragment correlations, specifically between their internal states. Information of this type is imprinted in the translational energies of the fragments, which can be measured using a number of recently developed translational spectroscopy methods. These data can provide detailed insights into the nature of the bond rupture process, as well as accurate values for the dissociation energy of the complexes. The focus of the present review is on experiments that provide correlated final state distributions for weakly bound binary complexes. Where possible, comparisons with theoretical calculations are made.