Molecule of the Month June 2013 |
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Nonradiative Relaxation of UV Excited Cytosine: From Fast to Ultrafast | ||
Cytosine exhibits a short S1 excited-state lifetime upon UV photoexcitation. We have measured the S0 → S1 vibronic spectrum [1] of supersonic jet-cooled cytosine. All observed vibronic excitations are overtone and combination bands of the low-frequency out-of-plane ν1 (butterfly), ν2 (boat) and ν3 (H-N-C6-H twist) vibrations. The lifetimes of the individual vibronic states are determined from the Lorentzian broadening of the band contours: At the vibrationless level, the lifetime is 44 picoseconds.
This work was carried out by Simon Lobsiger, Maria Trachsel and Hans-Martin Frey in the group of Prof. Samuel Leutwyler. References:
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