Vibrational resonance energy transfer and dephasing in liquid nitrogen near its boiling point: Molecular computations

Abstract

On the basis of current models of oscillator–oscillator and oscillator–anharmonicity–lattice coupling, the band broadening increments leading to the spontaneous width of the (near‐isotropic) Raman stretching fundamental of liquid nitrogen near its boiling point are predicted. Using known constants of the atom–atom Lennard‐Jones potential and known dynamic autocorrelation times of the system, the observed spontaneous bandwidth of 0.067 cm⁻¹ and its Lorentzian band contour are satisfactorily reproduced (0.07 cm⁻¹) by a vibrational dephasing mechanism if it is assumed that motional narrowing takes place through a modulation process decaying on the same fast time scale as that of the velocity correlation between two nitrogen molecules. On the other hand, resonance energy transfer contributes less than 1% to the band broadening.