Time and frequency resolved dynamics of ArBr2

Abstract

We report the first spectroscopic observation of and vibrational predissociation dynamics for ArBr(2). Measurements are reported for the linear and T-shaped isomers with time and frequency resolution near the Fourier limit of a 15 ps pulse. For the T-shaped isomer, the Ar-Br(2) bond energy D(0) for the B state, nu(')=19, is found to be 200 cm(-1), yielding a D(0)(X) value of 213 cm(-1). Product appearance rates are determined for nu(')=16-25 of the B state of ArBr(2). While the rate generally increases with increasing vibrational quantum number, the trend is not monotonic. Also, obtaining reproducible rates for any given vibrational level requires very careful control of the experimental conditions. The data suggest that ArBr(2) undergoes vibrational predissociation (VP) in the sparse intramolecular vibrational relaxation regime. These observations are consistent with theoretical calculations that show that T-shaped ArBr(2) undergoes VP in the sparse regime, such that lifetimes are strongly dependent on both the vibrational and rotational quantum numbers. As for ArI(2), a linear isomer of ArBr(2) is found to contribute a quasicontinuous background to the excitation spectra. Direct excitation of this continuum results in a very broad product vibrational distribution.

Competition between electronic and vibrational predissociation dynamics of the HeBr2 and NeBr2 van der Waals molecules

“…Error bars, which are 95% confidence intervals, are assigned using a numerical method described previously. 28 We have slightly modified the procedure to account for the possibility of a Ϯ4 ps error in the full width at half maximum of the laser cross-correlation. This is particularly important in the present experiment because many of the lifetimes are close to or less than the cross-correlation.…”

Real-time dissociation dynamics of the Ne2Br2 van der Waals complex

“…Studies on the dissociation of RgX 2 ͑Ј͒ complexes that require more than one quantum to dissociate show that the quanta are transferred sequentially rather than simultaneously, 9,47 so that these complexes dissociate via an IVR intermediate formed after the transfer of the first quantum rather than a direct VP mechanism. First, it gives a classical picture of the dissociation, ignoring quantum interference among the various pathways.…”

“…11,[46][47][48] With the 35 ps time resolution of our pump-probe setup, we have been able to record the time-dependent behavior of both the decay of the initial Rg-Br 2 and the formation of the Br 2 product. 11,[46][47][48] With the 35 ps time resolution of our pump-probe setup, we have been able to record the time-dependent behavior of both the decay of the initial Rg-Br 2 and the formation of the Br 2 product.…”

On the Unusual Properties of Halogen Bonds: A Detailed ab Initio Study of X2−(H2O)1−5 clusters (X = Cl and Br)

“…Thirty years ago, the halogens became a popular model system for studying nearest neighbor effects on spectroscopy with the advent of molecular beam studies of dimers and small clusters. , The expectation was that noble-gas interactions with halogens would provide a model system that could provide a framework for understanding systems that are more complicated. Again, however, this apparently simple model system proved to be more complicated than expected. − For instance, it took almost 30 years to work out the details of how different the spectroscopy is depending on whether the noble-gas atom is on the side of the halogen to form a T-shaped complex or on the end to form a linear complex. , For the T-shaped complex the noble-gas atom induces a relatively small spectral shift of the halogen valence electronic transitions of the halogens, from ∼3 cm −1 for helium to ∼20 cm −1 for Ar . The spectra exhibit well-defined rotational substructure that can be used to determine the bond lengths of the complexes.…”