Relaxation times measurement in single and multiply excited xenon clusters.

Direct measurement of the rates of nonradiative relaxation processes in electronically excited xenon clusters was carried out. The clusters were created in a pulsed supersonic beam and two-photon excited by femtosecond laser pulses with a wavelength of 263 nm. The measurements were performed using the pump-probe method and electron spectroscopy. It is shown that relaxation of light clusters XeN (N < 15) predominantly occurs by desorption of excited xenon atoms with a characteristic time constant of 3 ps. Heavier electronically excited clusters (N > 10) vibrationally relax to the lowest electronically excited state at a rate of about 0.075 eV/ps. Multiply excited clusters are deactivated via energy exchange between excited centers with the ionization of one of them. The production of electrons in this process occurs with a delay of ∼4 ps from the pump pulse, and the process is completed in 10 ps.

Relaxation channels of multi-photon excited xenon clusters.

The relaxation processes of the xenon clusters subjected to multi-photon excitation by laser radiation with quantum energies significantly lower than the thresholds of excitation of atoms and ionization of clusters were studied. Results obtained by means of the photoelectron spectroscopy method showed that desorption processes of excited atoms play a significant role in the decay of two-photon excited xenon clusters. A number of excited states of xenon atoms formed during this process were discovered and identified.

Mass-resolved two-photon and photoelectron spectra of ArXe in the region of Xe* 7p, 6p', 6d.

The two photon resonant, three photon ionization spectra of ArXe were recorded in the spectral region of 88,500-90,100 cm(-1). Seven new molecular band progressions dissociating to ArXe* → Ar(1)S0 + Xe* 7p[1/2]0, Xe* 7p[3/2]2, Xe* 6p'[3/2]2, Xe* 6p'[1/2]1, Xe* 6p'[1/2]0 have been selected and analyzed. The molecular constants for the excited states of ArXe* of these vibrational progressions were determined in the approximation of the anharmonic oscillator, the Morse potential and the Franck-Condon principle. The photoelectron spectra were recorded by several excited electronic-vibrational transitions of ArXe, the dissociation channels of the excited molecules were determined and extra information about the electron structure of the excited molecular states was obtained.

New supramolecular Au(I)-Cu(I) complex as potential luminescent label for proteins.

A novel supramolecular [Au6Cu2(C2C6H4-4-COONC4H4O2)6(Ph2PC6H4PPh2)3](PF6)2 complex functionalized with a succinimide ester alkynyl substituent has been synthesized and characterized using X-ray crystallography, mass spectrometry, and NMR spectroscopy. Like the other complexes of this class, it demonstrates bright emission in acetone and dichloromethane solutions with the excited state lifetime in a microsecond domain. This complex readily reacts with a surface amine group of proteins/enzymes (human serum albumin (HSA), rabbit anti-HSA antibodies, soybean trypsin inhibitor, and α-chymotrypsin) to give covalent conjugates, which contain up to five molecules of the luminescent label bound to the biomolecule. The conjugates keep a high level of the phosphorescent label emission, but in contrast to the parent complex molecule, display excellent solubility and high stability in physiological media. Investigation of the biological activity of the conjugates also showed that the specific structure of the biomolecules remained nearly unchanged upon bonding with the label, which is indicative of a very prospective of the conjugates application in biomolecular detection.