A MOLECULAR-DYNAMICS SIMULATION OF NBR TRAPPING IN AN ARGON MATRIX

A molecular dynamics model simulating the preparation of an argon matrix containing a NBr molecule is presented, and compared with recently reported experimental data. The present model reproduces the experimental spectral shift of the N-Br vibration in the most stable site reasonably well. The blue-shift of this single substitution site can be related to the shortened N-Br equilibrium distance, R(e), and to the increased restoring force acting on the nitrogen atom, that finds itself in an interstitial site. Under more stringent cooling conditions, some multiple substitution sites are formed; in these sites, motion is less hindered, the vibrational frequency and R(e) being similar to those of the free molecule.