Tris(2-amino-1,3-thia­zolium) hydrogen sulfate sulfate monohydrate

The centrosymmetric crystal structure of the novel semi-organic compound, 3C3H5N2S+·HSO4 −·SO4 2−·H2O, is based on chains of alternating anions and water mol­ecules (formed by O—H⋯O hydrogen bonds). The chains are inter­connected with the 2-amino-1,3-thia­zolium cations via strong N—H⋯O and weak C—H⋯O hydrogen-bonding inter­actions into a three-dimensional network

2-Amino-1,3-thia­zolium dihydrogen phosphate

In the title compound, C3H5N2S+·H2PO4 −, the dihydrogen phosphate anions form infinite chains along [001] via short O—H⋯O hydrogen bonds. The 2-amino­thia­zolium cations inter­connect these chains into a three-dimensional network by short linear or bifurcated N—H⋯O and weak C—H⋯O hydrogen bonds

Characterization of diode lasers and their application in monitoring of atmospheric pollution with photoacoustic detection

4 Summary This thesis work was concemed with the spectroscopic characterization of a set of newly developed GalnAsSb/AlGaSb lasers. The spectral range of their laser emission was studied in dependence on temperature and drive current. The relation of threshold current versus temperature was also studied. These basic characteristics were obtained using the methods of FT spectroscopy, classic absorption technique, and photoacoustic detection of gaseous phase molecules. On the basis of the described measurements, the composition of the semiconductor material was optimized in order to reach the maximum overlap of the laser emission over the methane absorption lines. The possibilities of combining the GaInAsSb/AlGaAsSb and InAsSb/lnAsSbP-based lasers with the FT spectroscopy were also studied and the modulated beam was used as the source of drive emission for the spectrometer. The diode lasers were used for the detection of a highly-resolved spectra of gases, and in connection with the photocoustic detection, low concentrations oť gaseous polltrtants could be determined, mainly with formaldehyde, ammonia and methane. Co-operation with the Department of Electrochemistry (the J. Heyrovsky lnstitute of Physical Chemistry) allowed us to use photoacoustic detection for a quantitative assessment of the ammonia..

Characterization of diode lasers and their application in monitoring of atmospheric pollution with photoacoustic detection

4 Summary This thesis work was concemed with the spectroscopic characterization of a set of newly developed GalnAsSb/AlGaSb lasers. The spectral range of their laser emission was studied in dependence on temperature and drive current. The relation of threshold current versus temperature was also studied. These basic characteristics were obtained using the methods of FT spectroscopy, classic absorption technique, and photoacoustic detection of gaseous phase molecules. On the basis of the described measurements, the composition of the semiconductor material was optimized in order to reach the maximum overlap of the laser emission over the methane absorption lines. The possibilities of combining the GaInAsSb/AlGaAsSb and InAsSb/lnAsSbP-based lasers with the FT spectroscopy were also studied and the modulated beam was used as the source of drive emission for the spectrometer. The diode lasers were used for the detection of a highly-resolved spectra of gases, and in connection with the photocoustic detection, low concentrations oť gaseous polltrtants could be determined, mainly with formaldehyde, ammonia and methane. Co-operation with the Department of Electrochemistry (the J. Heyrovsky lnstitute of Physical Chemistry) allowed us to use photoacoustic detection for a quantitative assessment of the ammonia...4 Shrnutí V rámci této disertačnípráce byla spektroskopicky charakterizována sada nově vyvinutých GaInAsSb/AlGaAsSb |aserťr. Byl zjišt'ován spektrální rozsah laserové emise v závislosti na teplotě a vstupním proudu a také závislost prahového proudu na teplotě' Tyo základní vlastnosti byly studovány metodami FT spektroskopie, klasické absorpční techniky a fotoakustické detekce rnolekul v plynné fázi. Na zák|adě těchto měření bylo optimalizováno složení polovodičového materiálu tak, aby doš]o k maximálnímu překryvu laserové emise s absorpčnímiliniemi methanu' Byly zkoumány a ukázány možnosti spojení FT spektroskopie s diodoými lasery na bázi GaInAsSb/AlGaAsSb a InAsSb/InAsSbP' jejichžmodulovaný svazek byl použit jako zdroj budícíhozáÍeni spektrometru. Diodové lasery byly vyrržity pro detekci vysoce rozlišených spekter plynů a ve spojení s fotoakustickou detekcí pro stanovení nízkých koncentrací plynných polutantů, předevšímformaldehydu, amoniaku a methanu. V rámci spolupráce s oddělením Elektrochemie (Ústav fyziká\ni chemie J. Heyrovského) byla metoda fotoakustické detekce pouŽita pro kvantitativní stanovení amoniaku generovaného elektrochemickou reakcí v systérnu 7-cyklodextrin - fu]leren' Byla zkonstruována zjednodušená fotoakustická cela s 3 cm rezonátorem. Tato cela umožnila detekci za tlaků vyšŠíchnež150...Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Characterization of diode lasers and their application in monitoring of atmospheric pollution with photoacoustic detection

Katedra fyzikální a makromol. chemieDepartment of Physical and Macromolecular ChemistryFaculty of SciencePřírodovědecká fakult

Turning solid aluminium transparent by intense soft X-ray photoionization

Saturable absorption is a phenomenon readily seen in the optical and infrared wavelengths. It has never been observed in core-electron transitions owing to the short lifetime of the excited states involved and the high intensities of the soft X-rays needed. We report saturable absorption of an L-shell transition in aluminium using record intensities over 10 16 W cm 2 at a photon energy of 92 eV. From a consideration of the relevant timescales, we infer that immediately after the X-rays have passed, the sample is in an exotic state where all of the aluminium atoms have an L-shell hole, and the valence band has approximately a 9 eV temperature, whereas the atoms are still on their crystallographic positions. Subsequently, Auger decay heats the material to the warm dense matter regime, at around 25 eV temperatures. The method is an ideal candidate to study homogeneous warm dense matter, highly relevant to planetary science, astrophysics and inertial confinement fusion. © 2009 Macmillan Publishers Limited. All rights reserved