Stark Effect and Torsional Motion

Interaction in Biphenyl

L. H. Coudert,a L. F. Pacios,b and J. Ortigosoc

aLISA, CNRS/Paris 12 University, Créteil, FrancebETSI Montes, Universidad Polytécnica de Madrid, Madrid, Spain

cIinstituto de Estructura de la Materia, CSIC, Serrano 121, Madrid, Spain

Overview

•The spectroscopy

•Stark interaction

•Alignment

Biphenyl is a non-rigid molecule

The torsional angle1 is 2

1. Merer and Watson, J. Mol. Spec. 47, 499 (1973)

z

x

y

The potential energy function

It has 90° periodicity

The potential energy function

eq.Pacios and Gómez, Chem.Phys. Letters 432, 414 (2006)

Torsional energy levels

Merer and Watson, J. Mol. Spec. 47, 499 (1973)

Stark interaction Hamiltonian

Polarizability tensor

Coupling between E and the large amplitude motion

Ramakrishna and Seideman, Phys. Rev. Letters 99, 103001 (2007)

Stark-rotation-torsion energy levels

Calculation I

Rigid case.

Non-rigid case

Kumar, Gross, Safvan, Rajgara, and Mathur, Phys. Rev. A 53, 3098 (1996)

E

Alignment

zZ

The stark interaction

energy is minimized

Calculation II

Rigid case.

Rigid case.

TK. Intensity = 3.6 1012 W·cm

<< |

Non-rigid case

Non-rigid case

TK. Intensity = 3.6 1012 W·cm

<< |

LaserBeam

Alignment rigid case

Zy

xz

LaserBeam

Alignment non-rigid case

Zy

xz

y

x

z

Non-rigid case: |

TK. No laser

TK. Intensity = 1013 W·cm

Non-rigid case: |