M.S. Rabasovic

Nonlinear microscopy of chitin and chitinous structures: a case study of two cave-dwelling insects

Abstract. We performed a study of the nonlinear optical properties of chemically purified chitin and insect cuticle using two-photon excited autofluorescence (TPEF) and second-harmonic generation (SHG) microscopy. Excitation spectrum, fluorescence time, polarization sensitivity, and bleaching speed were measured. We have found that the maximum autofluorescence signal requires an excitation wavelength below 850 nm. At longer wavelengths, we were able to penetrate more than 150-μm deep into the sample through the chitinous structures. The excitation power was kept below 10 mW (at the sample) in order to diminish bleaching. The SHG from the purified chitin was confirmed by spectral- and time-resolved measurements. Two cave-dwelling, depigmented, insect species were analyzed and three-dimensional images of the cuticular structures were obtained.

Time-Resolved LIBS Streak Spectrum Processing

The laser-induced breakdown spectroscopy (LIBS) is a sensitive tool for a rapid identification of the elemental composition of a sample regardless of the aggregate states and with a little sample preparation. The time-resolved LIBS system implemented in our laboratory is based on a Nd:YAG laser and an optical parametric oscillator (Vibrant 266). The detection part of our system is based on a Hamamatsu streak camera (C4334-01). Using advanced image processing techniques, we show how capabilities of basic software provided by Hamamatsu could be improved.

Time-Resolved Optical Spectra of the Laser-Induced Indium Plasma Detected Using a Streak Camera

We present time-resolved laser-induced breakdown spectroscopy (LIBS) spectra of atomic (In I) and ionic (In II) indium lines recorded in time ranges from 500 ns to 20 μs. Optical spectra have been acquired using a streak camera. Since it is assumed that the available supply of indium will slowly but inevitably diminish, the recycling of indium and finding the new natural sources are more and more important as the price of indium rises. The study of indium lines showed in this paper could be useful for making the LIBS detecting devices less expensive and more portable.

Comparison of beetroot extracts originating from several sites using time-resolved laser-induced fluorescence spectroscopy

Beetroot (Beta vulgaris) juice contains a large number of fluorophores which can fluoresce. There is a growing interest in beetroot extracts analysis. In contrast, there is only limited information about beetroot obtained without sample preparation and/or extraction of components from the sample. In this work, we continue our previous study (Rabasovic et al 2009 Acta Phys. Pol. A 116 570–2), analyzing and comparing beetroot extracts from several sites, using the time-resolved laser-induced fluorescence technique to measure the fluorescence of samples at different excitation wavelengths (340–470 nm) and for different sample dilutions.

Orange-Reddish Light Emitting Phosphor GdVO4:Sm3+ Prepared by Solution Combustion Synthesis

The gadolinium vanadate doped with samarium (GdVO4:Sm3+) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve the full crystallinity, the material was annealed in air atmosphere at 900°C. Phase identification in the postannealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscopy (SEM). Photoluminescence characterization of the emission spectrum and time-resolved analysis have been performed using the tunable laser optical parametric oscillator excitation and the streak camera. Several strong emission bands in the Sm3+ emission spectrum were observed, located at 567 nm (4G5/2–6H5/2), 604 nm (4G5/2–6H7/2), and 646 (654) nm (4G5/2–6H9/2), respectively. The weak emission bands at 533 nm (4F3/2–6H5/2) and 706 nm (4G5/2–6H11/2) and a weak broad luminescence emission band of VO43− were also observed by the detection system. We analyzed the possibility of using the host luminescence for two-color temperature sensing. The proposed method is improved by introducing the temporal dependence in the line intensity ratio measurements.