SELF-DENSITY FREQUENCY-SHIFT MEASUREMENTS OF RAMAN N2 Q-BRANCH TRANSITIONS

We report stimulated Raman investigations of N//2 Q-branch transitions in view to measure the self-density frequency shift. These measurements performed at 295 K over the density range 0. 02-0. 8 Amagat lead to a mean shift value equal to minus 5. 5 multiplied by 10** minus **3 cm** minus **1/ Amagat. Moreover, our data extrapolated at zero density allowed new refinements of the N//2 molecular constants: nu //0 equals 2329. 91165 (17) cm** minus **1, B//1 minus B//0 equals minus 0. 0173714 (22) cm** minus **1 and D//1 minus D// equals (7. 6 plus or minus 5. 0) multiplied by 10** minus **9 cm** minus **1.