RELAXATION OF HIGHLY VIBRATIONALLY EXCITED CYCLOHEPTATRIENE IN GASES AT HIGH-DENSITIES AND IN LIQUIDS

Vibrational relaxation of highly excited ground state 1,3,5-cyclohepta triene (CHT) has been investigated by picosecond transient absorption spectroscopy in gases (nitrogen and ethane) al pressures up to 200 bar and in the liquid solvents ethane, heptane, C2Cl3F3 and methanol. The results show that in the gas phase, the relaxation rates are proporti onal to the bath gas density within the studied pressure range. In con trast, the relaxation in liquids is significantly slower than predicte d by common models for the collision frequency at high densities.