Photochemical hole-burning in vibronic bands of the S₁ ← S₀ transition of free-base porphin in an n-octane crystal

The homogeneous linewidths of vibronic bands of the S1 ← S0 transition of free-base porphin (H2P) in an n-octane crystal at 4.2 K have been measured by photochemical hole-burning. Fourteen single vibronic levels were selectively excited in a 1600 cm-1 region above the origin. The holewidths vary strongly (by a factor of ≈ 40) as a function of the particular vibration excited and do not increase monotonically with energy. © 1979.