The microwave spectrum of the FeS radical

The rotational spectrum of the iron monosulfide radical, FeS, was measured in the frequency region of 220-390 GHz with a source-modulated millimeter/submillimeter-wave spectrometer. The radical was efficiently produced in a free space absorption cell by a dc discharge in a mixture of Ar and H₂S with a stainless-steel hollow cathode. Several series of paramagnetic lines were detected with intervals of about 12 GHz. The four series having relatively strong intensity were assigned to FeS in the vibrationally ground state of the X⁵Δ_i electronic state, two series to that in the vibrationally excited state, and five series presumably to FeS in the electronically excited state, . The effective molecular constants were determined for FeS in the X⁵Δ_i electronic state. The components of the vibrationally ground state showed an apparent shift from the typical pattern of the state. In addition, the fine structure of the state was found to be far from a regular pattern expected for a state. A trial analysis including electronic interaction between the and states was carried out, but it was not possible to explain the spectral lines of both electronic states simultaneously. Reasons for the heavily perturbed spectral patterns are discussed.     

Near-infrared diode laser spectroscopy of the HCSi radical

The , , and band spectra of HCSi radical were investigated by means of near-infrared diode laser spectroscopy to determine precise molecular constants for the and states. The detailed analysis of the rotationally resolved band spectra, studied for the first time in the present investigation, leads to the precise determination of molecular constants for the state associated with the Renner-Teller interaction. We obtained −0.15126663(53) and 495.00698(30) cm⁻¹ as the Renner-Teller parameter ε and the bending vibrational frequency ω₂, respectively. Based on the molecular constants for the and states, the rotational levels of the state were analyzed to obtain molecular constants and information on upper state perturbations. Using the available spectroscopic data, valence force fields for both the and states were estimated to aid in understanding the vibrational energy levels of the HCSi radical.     

Time-resolved spectroscopy of Al, Ti, and Mo X pinch radiation using an X-ray streak camera

Time-resolved spectroscopic measurements of the radiation emitted from Al, Ti, and Mo X pinches have been made with time resolution. The radiation is emitted from micropinch plasmas with sizes of order in times in the 10- range. Spectra implied that dense, plasmas were produced, such as a lifetime, 1.5- electron temperature and near solid-density Ti plasma. The experimental systems and analysis methods are described in detail, including line ratio calculations for μm-scale Ti and Al plasmas with ion densities of 10¹⁹-10²⁴ cm⁻³ and electron temperatures.     

MRCI studies on the electronic structure of AlN and AlN, and the electron affinity of AlN

Using multireference configuration-interaction methods and double to triple-zeta basis sets with semidiffuse and polarization functions, potential energies and spectroscopic constants for low-lying doublet, and quartet states of AlN⁻ were calculated. has R_e=3.280 bohr and . lies 0.17 eV above the ground state. Using an estimated electron affinity of 2.1 eV for AlN, four states of AlN⁻ are found to be stable, namely , , , and . Comparisons with the isovalent anions BN⁻ (three stable states) and AlP⁻ (seven stable states) are made. Photo-detachment of an electron from the state of AlN⁻ can lead to an accurate determination of the energy difference between the two close-lying lowest states of AlN, and , predicted here to be 0.09 eV apart.     

First CRDS-measurements of water vapour continuum in the 940 nm absorption band

Measurements of near-infrared water vapour continuum using continuous wave cavity ring down spectroscopy (cw-CRDS) have been performed at around 10611.6 and . The continuum absorption coefficients for N₂-broadening have been determined to be and at , and and at , respectively.These results represent the first near-IR continuum laboratory data determined within the complex spectral environment in the 940 nm water vapour band and are in reasonable agreement with simulations using the semiempirical CKD formulation.     

First-principles study of arsenic impurity clusters in molecular beam epitaxy (MBE) grown HgCdTe

The understanding of the microstructures of the arsenic tetramer , dimer , and singlet of HgCdTe is important to explain the high electrical compensation of molecular beam epitaxy (MBE) samples and the conversion to p-type behavior. The stable configurations were obtained from the first-principles calculations for the arsenic cluster defects [ (n=1, 2, and 4)] in as-grown HgCdTe. According to the defect formation energies calculated under Te-rich conditions, the most probable configurations of , , and have been established. For the optimized and the energy is favorable to combine in a nearest neighboring mercury vacancy , and the corresponding configurations can be used to explain the self-compensated n-type characteristics in as-grown materials. is likely to be more abundant than in as-grown materials, but arsenic atoms are more strongly bounded in than in , thus more substantial activation energy is needed for than that for . The atomic relaxations as well as the structural stability of the arsenic defects have also been investigated.     

Single crystal EPR studies of Mn(II) doped zinc sodium sulphate hexahydrate: a case of interstitial substitution

Single crystal Electron Paramagnetic Resonance studies on Mn(II) doped zinc sodium sulphate hexahydrate are carried out at room temperature. The angular variation spectra of the crystal in the three orthogonal planes show that the paramagnetic impurity Mn(II) has entered the host lattice interstitially. The spin Hamiltonian parameters calculated are: g_xx=1.899, g_yy=1.944, g_zz=2.024; and The probable location for the interstitial site has been identified from the position of various atoms in the lattice. The variable temperature study for polycrystalline sample has been carried out, which indicates no phase transition. The percentage covalency of Mn-O bond has been estimated to be 8.5%.     

Millimeter- and submillimeter-wave spectra of AuCl and AuBr in the XΣ electronic ground states

The millimeter- and submillimeter-wave spectra of AuCl and AuBr in the X¹Σ⁺ states were observed by employing a source-modulated microwave spectrometer. The AuCl and AuBr molecules were, respectively, generated in a free space cell by a d.c. glow discharge in Cl₂ and Br₂ with Ar. The gold atoms were supplied by the sputtering reaction from a gold sheet placed on the inner surface of a stainless-steel cathode. Rotational transitions of , , , and in highly excited vibrational states as well as in the ground vibrational states were measured in the region between 189 and 314 GHz. The transition frequencies were analyzed by a least-squares method using a combined-isotopomer Dunham-type term energy expression. The potential constants of gold halides obtained were compared with those of copper and silver halides.     

K-shell fluorescence yields for potassium and calcium compounds

The K-shell fluorescence yields for potassium and calcium compounds were investigated using a Si(Li) X-ray detector system ( at ). The target samples were excited using gamma rays from an ²⁴¹Am annular source of strength . Chemical effects on K-shell fluorescence yield for potassium and calcium were observed. The values were compared with theoretical values of pure potassium and calcium.     

Qualitative and quantitative analysis of lignite coal and its ash samples taken from Soma-Darkale region

Qualitative and quantitative analysis of lignite coal and its ash samples taken from Soma-Darkale region in city of Manisa (Turkey) have been performed by using the EDXRF technique. Samples are prepared from powder sifted by 200 mesh sieve.The elements Fe and Ba in the samples are analysed using the standard addition method. The samples were excited by gamma rays emitted from radioisotope source. The characteristic K X-rays emitted from samples were counted by means of Si(Li) detector which has a resolution at .