Breakdown Of Born-Oppenheimer Approximation Research Articles

Breakdown of Born‐Oppenheimer Approximation as a Physical Mechanism for Ultrafast Hydrogen Migrations in Strong Laser Driven Molecules

AbstractWe propose a physical mechanism based on breakdown of the Born‐Oppenheimer approximation to rationalize the ultrafast hydrogen migration in strong laser driven isomerization reactions. A three nuclei (proton, donor, and acceptor) model is employed to develop a three step solution scheme. The proton‐donor Coulomb repulsion is shown to be responsible for the high proton mobility. We identify a proton tunneling process and use the Keldysh‐Faisal‐Reiss theory to calculate the tunneling probability. The effect of laser parameters (intensity, frequency, polarization, and pulse duration) has been studied and found to be consistent with recent experiments.

Submillimeter-wave spectroscopy of the 15NCl radical: Determination of Born-Oppenheimer constants

Rotational transitions of 15N 35Cl and 15N 37Cl were observed in the submillimeter-wave region, and the observed spectrum was combined with the rotational and vibration-rotation spectra of other isotopic species previously reported to derive Born-Oppenheimer molecular constants. The breakdown of Born-Oppenheimer approximation has been clearly demonstrated for the rotational and spin-rotation interaction constants, whereas the effect was marginal for the spin-spin interaction constant. The equilibrium bond length has been recalculated from the B e constant thus corrected, to be 1.610 705 (19) Å, where the uncertainty given in parentheses is entirely due to that of Planck's constant.