Spectroscopy femtosecond transient absorption

The femtosecond transient absorption studies were performed with 387 nm laser pulses (1 khz, 150 fs pulse width) from an amplified Ti Sapphire laser system (Model CPA 2101, Clark-MXR Inc). A NOPA optical parametric converter was used to generate ultrashort tunable visible pulses from the pump pulses. The apparatus is referred to as a two-beam setup, where the pump pulse is used as excitation source for transient species and the delay of the probe pulse is exactly controlled by an optical delay rail. As probe (white light continuum), a small fraction of pulses stemming from the CPA laser system was focused by a 50 mm lens into a 2-mm thick sapphire disc. A schematic representation of the setup is given below in Fig. 7.2. 2.0 mm quartz cuvettes were used for all measurements. 

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Thomsen CL, Madsen D, Keiding SR, Thogersen J, Christiansen O. (1999) Two-photon dissociation and ionization of liquid water studied by femtosecond transient absorption spectroscopy./Chem Phys 110 3453-3462. 

N. Tamai and H. Masuhara, Femtosecond transient absorption spectroscopy of a spirooxazine photochromic reaction, Chem. Phys. Lett. 191, 189-194 (1992). 

Here, we briefly describe the laser ablation dynamics of phthalocyanine film where the primary species was confirmed, by femtosecond transient absorption spectroscopy [25], to be its electronically excited state. The exdton absorption band was replaced in 20 ps by a hot band of the ground electronic state. This rapid decay was ascribed to mutual interactions between densely formed excitons leading to sudden temperature elevation. The elevated temperature was estimated by comparing transient absorption spectra with the temperature difference ones. It is worth noting that quite normal dynamics of the excited states are detected, even under ablation conditions, which is the reason why we do not accept the plasma mechanism. Then we considered how to correlate these electronic processes of phthalocyanine films with their fragmentation. 

Fron, E., Pilot, R., Schweitzer, G., Qu, J., Herrmann, A., Muellen, K., Hofkens, J., Van der Auweraer, M., De Schryver, F. C., Photoinduced Electron Transfer in Perylenediimide Triphenylamine based Dendrimers Single Photon Timing and Femtosecond Transient Absorption Spectroscopy Photochem. Photobiol. Sci. 2008, 7, 597 604. 

Pritchina, E. A., Gritsan, N. P., Burdzinski, G. T., Platz, M. S., Study of Acyl Group Migration by Femtosecond Transient Absorption Spectroscopy and Computational Chemistry, J. Phys. Chem. A 2007, 111, 10483 10489. 

Direct observation of the CTI process in real time has been performed by use of femtosecond pulses. In 1991, two groups first reported femtosecond transient absorption spectroscopy of bovine rhodopsin [44,45], but their conclusions were remarkably divergent. One group excited bovine rhodopsin with a 35 fs pulse and probed with a 10 fs pulse, and concluded that product formation completed within 200 fs [44], In contrast, the other group measured transient absorption of bovine... 

Kinetics and thermodynamics of electron injection and charge recombination DNA hairpins possessing a stilbenediether electron donor linker observed with neighboring cytosine or thymine bases obtained by femtosecond transient absorption spectroscopy were investigated [12]. 

Tamaki, Y., et al., Dynamics of efficient electron-hole separation in Ti02 nanoparticles revealed by femtosecond transient absorption spectroscopy under die weak-excitation condition. Physical Chemistry Chemical Physics, 2007. 9(12) p. 1453-1460. 

In 1999, the research groups of Lewis and Wasielewski reported femtosecond transient absorption spectroscopy studies of the electron injection to DNA from the pho-toexcited Sd introduced at the loop position of the DNA hairpin. When Sd next to T is excited, charge separation occurs within 0.2ps, indicating the excess electron injection to T. When one or two G G base pairs, which act as a barrier for excess electron injection, were inserted between Sd and A T pairs, the electron injection rate decreased to 5.7 x 10 or 4.4xl0 s, respectively. ... 

Martinsson, P., Oksanen, J.A., Hilgendorff, M., Hynninen, P.H., Sundstrom, V., et al. Dynamics of ground and excited state chlorophyll a molecules in pyridine solution probed by femtosecond transient absorption spectroscopy. Chem. Phys. Lett. 309, 386-394 (1999)... 

However, the formation of azepine 51, upon photolysis of 47, in inert gas matrices was not fully understood. Nevertheless, it was reasonably explained by the formation of 51 in the reaction of the hot singlet nitrene, 152. ° This hypothesis is consistent with the results of recent studies of the photolysis of 47 and a series of its simple derivatives in solution at room temperature by femtosecond transient absorption spectroscopy and femtosecond IR spectroscopy. ... 

The spectrum (Amax = 410nm) and kinetics of singlet ortfto-biphenylnitrene 67a were recorded by LFP of 65a in glassy 3-methylpentane at 77 K. The lifetimes of 67a and 67-d9 at 77 K are equal to 59 3ns and 80 + 2ns, respectively. A similar spectrum was detected recently at room temperature using femtosecond transient absorption spectroscopy (Figures 11.16 and 11.17). " ... 

The photochemistry of naphthyl azides 79 and 80 in solution at ambient temperature has been studied using LFP ° and TRIR techniques and the femtosecond transient absorption spectroscopy. LFP study of naphthyl azide photochemistry in glassy solvents at 77 K has also been performed. ... 

Guo, L., Wang, Y, and Lu, H. P. (2010) Combined single-molecule photon-stamping spectro scopy and femtosecond transient absorption spectroscopy studies of interfacial electron transfer dynamics, J. Am. 

Ground State and Femtosecond Transient Absorption Spectroscopy of a Mutant of Rhodobacter capsulatus which Lacks the Initial Electron Acceptor Bacteriopheophytin... 

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