Elena Samoylova

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The excited-state dynamics of adenine and thymine dimers and the adenine-thymine base pair were investigated by femtosecond pump-probe ionization spectroscopy with excitation wavelengths of 250-272 nm. The base pairs showed a characteristic ultrafast decay of the initially excited pi pi* state to an n pi* state (lifetime tau(pi pi*) approximately 100 fs)(More)
We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 +/- 10 picoseconds(More)
We report the relaxation dynamics of keto and enol or keto-imino cytosine, photoexcited in the wavelength range of 260-290 nm. Three transients with femtosecond to hundreds of picoseconds lifetimes are observed for the biologically relevant keto tautomer and are assigned to internal conversion and excited-state tautomerization. Only two transients with(More)
Hemithioindigo (HTI) photoswitches have a tremendous potential for biological and supramolecular applications due to their absorptions in the visible-light region in conjunction with ultrafast photoisomerization and high thermal bistability. Rational tailoring of the photophysical properties for a specific application is the key to exploit the full(More)
Femtosecond pump-probe spectroscopy was combined with photoelectron-photoion coincidence detection to investigate the electronic structure and dynamics of isolated adenine (A) and thymine (T) dimers and the adenine-thymine (AT) base pair. The photoelectron spectra show that pipi* and npi* states are only weakly perturbed in the hydrogen-bound dimers as(More)
We present femtosecond pump-probe mass and photoelectron spectra for adenine (A) and microhydrated A(m)(H(2)O)(n) clusters. Three distinct relaxation processes of photoexcited electronic states were distinguished: in unhydrated A, relaxation of the optically bright pipi* state occurred via the dark npi* state with respective lifetimes of <0.1 and 1.3 ps. In(More)
Ab initio calculations and femtosecond pump-probe ionization experiments were carried out to identify excited state relaxation processes in isolated thymine monomer and small thymine-water clusters. Three transient species with life times of < or =100 fs, 7 ps and >1 ns were observed in the experiments on gas phase thymine. The longer-lived transients were(More)
Ab initio calculations and time-resolved photoionization spectroscopy were carried out to characterize the role of the lowest two pi sigma* excited states for the photoinduced processes in the adenine monomer, adenine dimer, and adenine-water clusters. The calculations show--with respect to the monomer--a stabilization of 0.11-0.14 eV for the pi sigma*(More)
Twisted intramolecular charge transfer (TICT) formation in hemithioindigo photoswitches has recently been reported and constitutes a second deexcitation pathway complementary to photoisomerization. Typically, this behavior is not found for this type of photoswitches, and it takes special geometric and electronic conditions to realize it. Here we present a(More)
The article deals with the influence of meteorological factors on the activity of the taiga tick Ixodes persulcatus Sch. in the city of St. Petersburg and its environs. The results of correlation analysis of meteorological data (21 parameters) and tick collection data for 1980-2012 demonstrated a linear dependence between 11 meteorological parameters and(More)