Observation of a free rotation transient in hot stilbene vapor

✍ Scribed by A.B. Myers; P.L. Holt; M.A. Pereira; R.M. Hochstrasser

• Book ID: 103026433
• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 580 KB
• Volume: 130
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(86)80467-5

✦ Synopsis

The fluorescence anisotropy decay of collision-free trans-stilbene vapor at 463 K has been measured with 5 ps time resolution using fluorescence up-conversion. The anisotropy measured with 302 nm excitation shows a pulsewidth-limited decay attributed to free rotation followed by a constant value at longer times. The long-time anisotropy of 0.069 is close to the theoretical regular rotor value of 0.074, indicating minimal vibration-rotation energy transfer on a time scale of z 50 ps. Comparison with the longtime anisotropies previously observed using shorter excitation wavelengths indicates that the rotational motion becomes more nearly statistical with increasing excess vibrational energy.