Laser induced fluorescence study of the F+I2→IF+I reactive collision

Abstract

We have performed a crossed beam study of the F+I2→IF+I reaction. The IF product was detected by the LIF technique, using a cw single frequency dye laser. About 10 000 lines belonging to the B–X system of IF have been thus recorded. These lines have been assigned and the populations of about 1300 rovibrational levels of the X state were deduced from their intensities. This analysis takes into account the coherent saturation regime of the excitation process. In the present work, only the high vibrational levels of the X state (v″=8–20) have been studied. A striking result is the observation of bimodal rotational distributions for several vibrational levels: the rotational distribution presents a plateau and a peak for high rotational quantum numbers. The vibrational distribution presents a peak centered at v″=13, and as we have shown that the v″=0 peak observed by other authors is in fact an experimental artifact, the general features of the energy disposal in this reaction are now well known.

Quantitative Calculation of Product Rovibrational Distributions from Atom−Diatom Exchange Reactions

“…The F + I 2 ( v i , j i ) → IF ( v f , j f ) + I reaction is of interest for a number of reasons. The use of a narrow line probe laser allowed Girard et al , to resolve rotational distributions for the very large numbers of vibrational and rotational states of the product IF molecules emerging from this reaction and thus the reproduction of these constitutes a stringent test of any model. Furthermore, the rotational distribution in many of the v f states is bimodal, a subject much discussed in the context of this and other reactions. , Quasi-classical trajectory (QCT) methods have been employed to predict the outcome of this reaction , in which the number of open states makes a quantum mechanical (QM) calculation impractical.…”

Photodissociation of ICl Molecule Oriented by an Intense Electric Field: Experiment and Theoretical Analysis

“…The experiment was performed in our crossed beam machine already described and the modifications done for the present experiment are described in our previous paper …”

Reactive scattering of a supersonic fluorine atom beam: F + I2

“…Further reactive scattering measurements have therefore been undertaken I-4] at a lower initial translational energy E ~ 20kJmo1-1 using a supersonic beam of F atoms seeded in Ne buffer gas, in order to facilitate comparison with the IF product rotational-vibrational state distributions. Early Monte Carlo trajectory calculations [1][2][3][4][5] suggested the occurrence of migratory dynamics in the F + 12 reaction and the subsequent reactive scattering [1,4] and laser-induced fluorescence measurements [2,3] have been interpreted on this basis. More recently the topography of the F + I2 potential energy surface has been investigated in a trajectory study [1][2][3][4][5][6], which demonstrates that a second potential energy well in the IFI configuration is responsible for the occurrence of migratory trajectories, in 0026 addition to the potential energy well in the FII configuration which was identified in the previous trajectory study [5].…”

“…Rotational-vibrational state distributions have also been measured for IF products by laser-induced fluorescence spectroscopy [2,3] but at a much lower initial translational energy E ~ 11 kJmo1-1. Further reactive scattering measurements have therefore been undertaken I-4] at a lower initial translational energy E ~ 20kJmo1-1 using a supersonic beam of F atoms seeded in Ne buffer gas, in order to facilitate comparison with the IF product rotational-vibrational state distributions.…”