Hole burning, transient

Pump-probe absorption experiments on the femtosecond time scale generally fall into two effective types, depending on the duration and spectral width of the pump pulse. If tlie pump spectrum is significantly narrower in width than the electronic absorption line shape, transient hole-burning spectroscopy [101. 102. 103. 104. 105. 106. 107. 108. 109. 110. 111. 112 and 113] can be perfomied. The second type of experiment, dynamic absorption spectroscopy [57, 114. 115. 116. 117. 118. 119. 120. 121 and 122], can be perfomied if the pump and probe pulses are short compared to tlie period of the vibrational modes that are coupled to the electronic transition. 

Figure B2.1.6 Femtosecond spectrometer for transient hole-burning spectroscopy with a continuum probe. Symbols used bs, 10% reflecting beamsplitter p, polarizer. The continuum generator consists of a focusing lens, a cell containing flowing water or ethylene glycol or, alternatively, a sapphire crystal and a recollimating lens.

Figure B2.1.7 Transient hole-burned speetra obtained at room temperature with a tetrapyrrole-eontaining light-harvesting protein subunit, the a subunit of C-phyeoeyanin. Top fluoreseenee and absorption speetra of the sample superimposed with die speetnuu of the 80 fs pump pulses used in the experiment, whieh were obtained from an amplified CPM dye laser operating at 620 mn. Bottom absorption-diflferenee speetra obtained at a series of probe time delays.

In some extremely iimovative recent experiments, Hochstrasser and co-workers [ ] have described IR transient hole-burning experiments focused on characterizing inliomogeneous broadening in the amide 1... 

Kinoshita S 1989 Theory of transient hole-burning spectrum for molecules in solution J. Chem. Phys. 91 5175-84... 

Kang T J, Yu J and Berg M 1990 Rapid solvation of a nonpolar solute measured by ultrafast transient hole burning Chem. Phys. Lett. 174 476-80... 

Murakami H, Kinoshita S, Hirata Y, Okada T and Mataga N 1992 Transient hole-burning and time-resolved fluorescence spectra of dye molecules in solution evidence for ground-state relaxation and hole-filling effect J. Chem. Phys. 97 7881-8... 

Ma J, Bout D V and Berg M 1995 Solvation dynamics studied by ultrafast transient hole burning J. Moi. Liq. 65/66 301-4... 

Edington M D, Riter R E and Beck W F 1997 Femtosecond transient hole-burning detection of interexciton-state radiationless decay in allophycocyanin trimers J. Phys. Chem. B 101 4473-7... 

As evidenced from the above discussion, vibrational line shapes provide information mostly about intermolecular structure. Transient hole burning and more recently echo experiments, on the other hand, can provide information about the dynamics of spectral diffusion. The first echo experiments on the HOD/ D2O system involved two excitation pulses, and the signal was detected either by integrating the intensity [20] or by heterodyning [22]. The experiments were analyzed with the standard model assuming Gaussian frequency fluctuations. The data were consistent with a spectral diffusion TCF that was bi-exponential, involving fast and slow times of about 100 fs and 1 ps, respectively. 

Transient hole burning is clearly indicated by the data for the anisotropic component of the probe transmission change (a, b) with a halfwidth (true FWHM) of 45 5 cm-1 of the Lorentzian shaped hole at early delay times, tD < 0 (a). For the isotropic component of the probing signal, the narrow hole (dotted lines in d, e) is superimposed on a broader... 

Laenen R, Rauscher C. Transient hole-burning spectroscopy of associated ethanol molecules in the infrared structural dynamics and evidence for energy migration. J Chem Phys 1997 106 1-7. 

Yu J, Fourkas JT, Berg M. Transient hole burning studies of electronic state solvation phonon and structural contributions. In Martin J-L, Migus A, Mourou G, Zewail AH, eds. Ultrafast Phenomena VIII. Berlin Springer-Verlag, 1992. 

Cavanagh MC, Martini IB, Schwartz BJ. (2004) Revisiting the pump-probe polarized transient hole-burning of the hydrated electron Is its absorption spectrum inhomogeneously broadened Chem Phys Letts 396 359-366. 

The time-resolved solvation of s-tetrazine in propylene carbonate is studied by ultrafast transient hole burning. In agreement with mode-coupling theory, the temperature dependence of the average relaxation dme follows a power law in which the critical temperature and exponent are the same as in other relaxation experiments. Our recent theory for solvation by mechanical relaxation provides a unified and quantitative explanation of both the subpicosecond phonon-induced relaxation and the slower structural relaxation. 

We used transient hole burning to measure the solvation dynamics (Fig. 1).[3-S] These experiments yield both a time-dependent Stokes shift and a time-dependent width, both of which are related to the solvation dynamics. Here we consider the time-dependent Stokes shift. The time-dependent widths will be discussed elsewhere.[9]... 

Fig. 2 A fit of a viscoelastic model of solvation (solid) to transient hole burning data (points). Temperatures top to bottom 160K to 298K...

It is not surprising that the triplet states of porphyrins attract interest. A comprehensive study of some purpurins with Sn(lV) substitution involving observations of absorption, fluorescence and triplet spectra and 2 formation and the triplet state of sapphyrin dication (a large porphyrin like system) shows an unusual spin alignment in the monomer and spin delocalization in dimers " are systems of photophysical interest. The influence of external parameters on time resolved transient hole burning in porphyrins shows the effects of a triplet state bottleneck in the rate of state build up". ... 

Fig. 20 a Transient hole burning spectra of [Rh(bpy)3][NaAl1 xCrx(ox)3]C104 at 1.5 K for different values of x. b The observed linewidth as a function of x... 

Pump-probe absorption experiments on the femtosecond time scale generally fall into two effective types, depending on the duration and spectral width of the pump pulse. If the pump spectrum is significantly narrower in width than the electronic absorption line shape, transient hole-burning spectroscopy [101. 102. 

As an example, a series of transient hole-burning spectra obtained with a chirp-compensated continuum probe with a light-harvesting protein is shown in figure B2.1.7 [112]. As the probe delay increases, the initially... 

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