Hexapole-Oriented Asymmetric-Top Molecules and Their Stereodirectional Photodissociation Dynamics

Abstract

Abstract.Molecular orientation is a fundamental requisite in the study of stereodirected dynamics of collisional and photoinitiated processes. In this last decade, variable hexapolar electric filters have been developed and employed for the rotational-state selection and the alignment of molecules of increasing complexity, for which main difficulties are their mass, their low symmetry and the very dense rotational manifold. In this work, for the first time, a complex molecule such as 2-bromobutane, an asymmetric-top containing a heavy atom (the bromine), has been successfully oriented by a weak homogeneous field placed downstream the hexapolar filter.Efficiency of the orientation has been characterized experimentally, by combining time-of-flight measurements and a slice-ion-imaging detection technique. The application is described to the photodissociation dynamics of the oriented 2-bromobutane, which was carried out at a laser wavelength of 234 nm, corresponding to the breaking of the C -Br bond. The Br photofragment is produced in both the ground Br ( 2 P3/2) and the excited Br ( 2 P1/2) electronic states and both channels are studied by the slice imaging technique, revealing new features in the velocity and angular distributions with respect to previous investigations on non-oriented molecules. 3 1. Introduction.

Transient isomers in the photodissociation of bromoiodomethane

“…Similarly, the cleavage energies for the C-Br and C-I bonds hold in gas phases for the more complex photoinitiated dissociation reaction of the analogous bromobutane. 75,76 The same observations hold in solution phase. 72,73,[77][78][79][80] Either Kwok et al 73 and Zheng and Phillips 77 pointed out that CH 2 Br-I, which is observed in cyclohexane, could undergo an intramolecular reorganization to form a second geometrical isomer CH 2 I-Br; see the reaction scheme in Fig.…”

Rovibrationally Excited Molecules on the Verge of a Triple Breakdown: Molecular and Roaming Mechanisms in the Photodecomposition of Methyl Formate

“…These vectors have been inferred from the simulated 2D projection of the threedimensional photofragment angular distribution ( Fig. 2b) (details on the vector correlation of the photodissociation of the oriented 2-bromobutane are given in Nakamura et al 21 ).…”

Stereodynamic Imaging of Bromine Atomic Photofragments Eliminated from 1-Bromo-2-methylbutane Oriented via Hexapole State Selector

“…If the backward orientation is endorsed, a biased pulse should be implemented inside the ion lens to reverse the direction. 5 A 308 nm XeCl excimer laser (LPX 200, Lambda Physik) -pumped dye laser (PD 3000, Lambda…”