by S. Kudryashov, A. Samokhvalov, S. Shelygina, A. Karabutov, G. Tsibidis, D. Pankin, V. Veiko
Laser Physics Letters, 17, 105302, 1-6.
The ultrasonic characterization of the propagation of femtosecond laser pulses in pure transparent water and colored phenol-red dye solutions at variable concentrations indicates their thermoacoustic pressure generation due to intrinsic multi-photon absorption in the low-power sub-filamentation regime and sub-linear pressure response of sub-critical plasma via free-carrier absorption in the filamentation regime. Multi-photon absorption appears to be concentration dependent for water and dye solutions, while plasma absorption demonstrates a universal trend for all these liquids. In the filamentation regime, through the non-linear laser-matter interactions, not only new optical frequencies (intense white-light supercontinua) were generated, but supercontinuum-based ultrafast broadband spectroscopy in the filaments also revealed many additional transient absorption bands of the dye molecules, induced via power-dependent and concentration-independent stimulated Raman scattering.
by D. S. Prokuratov, A. S. Davtian, O. S. Vereshchagin, N. S. Kurganov, A. A. Samokhvalov, D. V. Pankin, A. V. Povolotckaia, A. A. Shimko, A. A. Mikhailova, P. A. Somov, V. A. Parfenov
Optical and Quantum Electronics, 52(2), 113, 1-12
The paper presents the results of research investigating the possibility of applying laser cleaning for controlled layer-by-layer removal of iron corrosion from gilded silver foil on a medieval nomad’s belt pad. Lasers irradiated at the wavelengths of 355, 532, 1064 nm, 2.97, 10.6 μm were tested. A comparison of pulse durations of 100 μs, 100, 8, 6 ns, 75 ps, 100 fs were conducted. Corrosion samples were irradiated in various media: air, argon atmosphere, water, ethanol, engine oil, glycerin. In all of these cases removing of material occurred, but it was accompanied by surface blackening due the burnt organics and to thermal transformation of the goethite and lepidocrocite into magnetite. The best results from the point of view of achieving delicate cleaning and minimal conversion of goethite to magnetite were obtained by the Ti:Sa laser with a 100 fs pulse duration.
23 января в 11.00 в здании РЦ ОЛМИВ по адресу Петергоф, Ульяновская 5, ауд.209 состоится лекция заслуженного деятеля науки Российской Федерации, д.т.н. Добрусиной Светланы Александровны.
Тема лекции: "Деструкция бумаги в процессе естественного старения. Изменение свойств бумаги в процессе старения. Влияние факторов окружающей среды на свойства бумаги Причины и виды повреждений. Долговечная бумага. Свойства."