Features of the near-infrared phosphorescence of singlet oxygen 1 O 2 photosensitized by TiO 2 in solutions have been investigated. The short-lived phosphorescence of 1 O 2 with spectral maximum at approximately 1300 nm is observed to follow excitation by pulsed laser radiation at 355 nm of TiO 2 suspended in CCl 4 and water H 2 O. The shorter lifetime and spectral shift of this phosphorescence, as compared with phosphorescence of 1 O 2 sensitized by phenalenone in these solvents, are attributed to the adsorbed state of emitting singlet oxygen. The observed laser pulse energy dependence indicates the two-photon and three-photon nature of this phosphorescence initiation in CCl 4 and H 2 O, respectively. The formation of 1 O 2 in CCl 4 is assumed to be provided by the sequence of one-photon excitation of TiO 2 , giving rise to superoxide anion O 2 − and one-photon photodetachment of electron from O 2 − . The photodetachment of electron from O 2 − in water H 2 O is a two-photon process because of higher solvation energy of superoxide anion in water. The processes that govern the rise and decay of singlet oxygen phosphorescence sensitized by TiO 2 are discussed. The factors affecting the yield of singlet oxygen provided by electron photodetachment are also considered.
The CH(3)I A-state-assisted photofragmentation of the (CH(3)I)(2) van der Waals dimer at 248 nm and nearby wavelengths has been revisited experimentally using the time-of-flight mass spectrometry with supersonic and effusive molecular beams and the "velocity map imaging" technique. The processes underlying the appearance of two main (CH(3)I)(2) cluster-specific features in the mass spectra, namely, I(2)(+) and translationally "hot" I(+) ions, have been studied. Translationally hot I(+) ions with an average kinetic energy of 0.94+/-0.02 eV appear in the one-quantum photodissociation of vibrationally excited I(2)(+)((2)Pi(32,g)) ions (E(vib)=0.45+/-0.11 eV) via a "parallel" photodissociation process with an anisotropy parameter beta=1.55+/-0.03. Comparison of the images of I(+) arising from the photoexcitation of CH(3)I clusters versus those from neutral I(2) shows that "concerted" photodissociation of the ionized (CH(3)I)(2)(+) dimer appears to be the most likely mechanism for the formation of molecular iodine ion I(2)(+), instead of photoionization of neutral molecular iodine.
A graphene solution to conductivity mismatch: Spin injection from ferromagnetic metal/graphene tunnel contacts into silicon J. Appl. Phys. 113, 17C502 (2013); 10.1063/1.4793712Spin-polarized state transport from ferromagnetic to conductive material: Signal amplification by ferromagnetic layer J. Appl. Phys. 112, 084310 (2012); 10.1063/1.4759132Nanoscale magnetic structure and properties of solution-derived self-assembled La0.7Sr0.3MnO3 islandsIn the present study, a quantum filter of spin-polarized states induced by magnetic fields in an iron nanolayer was assembled and experimentally studied. We found the device to pass certain spinpolarized states from the iron nanolayer to a conductive gold nanolayer through a dielectric silicon dioxide nanolayer. A theoretical model developed earlier was successfully applied to qualitatively interpret the experimental data.
Silicon nitride films of different stoichiometric composition were studied using Raman spectroscopy. A Raman signal due to Si–Si, Si–N bond vibrations in silicon nanoclusters was detected in as-deposited films. The appearance of Raman peaks in the range 493–514 cm−1 after thermal and pulse laser treatments was interpreted as formation of silicon nanocrystals with sizes from 1.3 up to 5 nm depending on treatment parameters. Thermal treatment at 1200 °C allowed Si atom diffusion and its gathering in Si nanocrystals, meanwhile 5 ns pulse laser irradiation leads to crystallization of preexisting silicon nanoclusters inside the as-deposited SiNx films.
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