Laser-induced time-resolved luminescence of orange kyanite Al_2SiO_5

Manganese is a very important microelement performing a large number of biological functions in human body. We have detected by spectroscopic measurements manganese in mineral kyanite. In this paper we present laser-induced time-resolved luminescence and optical absorbance spectra of orange, Mn containing kyanite. It was proven the orange color is caused by Mn^(3+). Several luminescence lines and bands were found and ascribed to Mn^(4+) and Mn^(3+), emission centers. The spectroscopic technique can be utilized for detection of small amounts of manganese in minerals

The nature of unusual luminescence in natural calcite, CaCO3

The unusual luminescence of particular varieties of natural pink calcite (CaCO{sub 3}) samples was studied by laser-induced time-resolved luminescence spectroscopy at different temperatures. The luminescence is characterized by intense blue emission under short-wave UV lamp excitation with an extremely long decay time, accompanied by pink-orange luminescence under long wave UV excitation. Our investigation included optical absorption, natural thermostimulated luminescence (NTL) and Laser-Induced Breakdown Spectroscopy (LIBS) studies. Two luminescence centers were detected: a narrow violet band, with {lambda}{sub max} = 412 nm, {Delta} = 45 nm, two decay components of {tau}{sub 1} = 5 ns and {tau}{sub 2} = 7.2 ms, accompanied by very long afterglow, and an orange emission band with {lambda}{sub max} = 595 nm, {Delta} = 90 nm and {tau} = 5 ns. Both luminescence centers are thermally unstable with the blue emission disappearing after heating at 500 C, and the orange emission disappearing after heating at different temperatures starting from 230 C, although sometimes it is stable up to 500 C in different samples. Both centers have spectral-kinetic properties very unusual for mineral luminescence, which in combination with extremely low impurity concentrations, prevent their identification with specific impurity related emission. The most likely explanation of these observations may be the presence of radiation-induced luminescence centers. The long violet afterglow is evidently connected with trapped charge carrier liberation, with their subsequent migration through the valence band and ultimate recombination with a radiation-induced center responsible for the unusual violet luminescence

Laser-induced breakdown spectroscopy of Br and I molecules with alkali-earth elements

International audienceIn general, bromine and iodine do not produce atomic or ionic emission lines of sufficient intensity to permit their sensitive detection by laser-induced breakdown spectroscopy in air. This situation is mainly due to both their high excitation levels and the position of their strongest emission lines being either in the VUV or NIR range. However, these two elements recombine with alkali-earth elements Ca and Ba to form molecules with intense and characteristic molecular bands that emit in the visible range. Such molecular detection represents a complementary method for LIBS analytical detection of Br and I, which has not been used before. In this paper, we aim to show that these broad emission molecular bands may be useful for many analytical tasks, as these reactions also occur with other halogens, such as F and Cl

Red photoluminescence and purple color of naturally irradiated fluorite

Natural radiation-induced red fluorescence of fluorite consists of two broad bands at 750 and 635 nm with very short decay times of 20.3 and less than 5 ns, respectively. The first one is connected to an M center compensated by Na, while the second is connected to an M⁺ center, possibly formed as result of the M center’s destruction by UV irradiation. The optically active centers in naturally irradiated fluorite responsible for red luminescence and purple color are different from one another. The most probable reason for the purple color is colloidal calcium and not the M_(Na) center

Red photoluminescence and purple color of naturally irradiated fluorite

Natural radiation-induced red fluorescence of fluorite consists of two broad bands at 750 and 635 nm with very short decay times of 20.3 and less than 5 ns, respectively. The first one is connected to an M center compensated by Na, while the second is connected to an M⁺ center, possibly formed as result of the M center’s destruction by UV irradiation. The optically active centers in naturally irradiated fluorite responsible for red luminescence and purple color are different from one another. The most probable reason for the purple color is colloidal calcium and not the M_(Na) center

Detection of illicit chemicals by portable Raman spectrometer

The Raman spectrometers can be built as the portable devices and can be used in various places to detect illicit chemicals. This method has become popular due to deficiency of other fast methods that could be applied against terrorist attacks or could help police at their work. The Conception of a portable Raman spectrometer has been presented. The Description enclosures the presentation of the prepared device and its possible applications by presenting exemplary detection results

CVD grown copper tungstate thin films for solar water splitting

In this paper, a direct chemical vapor deposition (CVD) approach is applied for the first time to synthesize high quality copper oxide (CuO), copper tungstate (CuWO4) and tungsten oxide (WO3) on F:SnO2 (FTO) substrates for photocatalytic water splitting.</p