9.5.1.3 Tryptophan
The case of tryptophan (Trp) is different because no vibrationally resolved spectra
could be realised under similar experimental conditions. This is due to the very
short excited-state lifetime, in the femtosecond range (between 10 and 100 fs),
which is indicative of a very efficient non-radiative process in Trp as will be
discussed in the next sections.
9.5.2 Comparison Between Spectroscopic Results and Ab-initio
Calculations
Since the experimental spectroscopy of protonated molecules has made tremendous
progress, it is worthwhile to compare with the results from recent ab-initio methods.
This will give some confidence in the calculations, which is particularly necessary to
230
240
250
260
270
280
290
44000
42000
40000
38000
36000
Wavenumbers (cm
-1
)
Wavelength (nm)
107 amu
108 amu
119 amu
136 amu
181 amu
Fig. 9.6 Photofragmentation spectrum of
protonated tyrosine as a
function of excitation
wavelength obtained in an ion
trap at around 50 K. The
spectrum changes with the
detected fragment
166
C. Dedonder et al.