Lateral PbS Photovoltaic Devices for High Performance Infrared and Terahertz Photodetectors

We fabricated a lateral photovoltaic device for use as infrared to terahertz (THz) detectors by chemically depositing PbS films on titanium substrates. We discussed the material properties of PbS films grown on glass with varying deposition conditions. PbS was deposited on Ti substrates and by taking advantage of the Ti/PbS Schottky junction, we discussed the photocurrent transients as well as the room temperature spectrum response measured by Fourier transform infrared (FTIR) spectrometer. Our photovoltaic PbS device operates at room temperature for wavelength ranges up to 50 µm, which is in the terahertz region, making the device highly applicable in many fields.

The NH2 scissors band of methylamine

For the first time the ν4 NH2 scissors band has been assigned in a high-resolution infrared spectrum. A rotationally resolved spectrum of methylamine was recorded using two infrared spectroscopic techniques. A White-type multi-pass cell device coupled to the Bruker IFS 125 HR Fourier transform spectrometer was implemented on the AILES beamline at the SOLEIL synchrotron facility and a room-temperature spectrum of the whole band in the region of 1540–1710 cm−1 was recorded with a resolution of 0.001 cm−1. Then, a low-temperature high-resolution spectrum in the 1622.5–1655.6 cm−1 range of Q and R branches of the ν4 band was recorded using a quantum cascade laser spectrometer. Preliminary assignment was carried out in the NH2 scissors band region, and about 2200 transitions for K from 0 to 6 have been assigned for A, B, and E1 symmetry species. The simultaneous fit of assigned lines using a group-theoretical effective Hamiltonian was not successful; instead simple polynomial series expansions were used for each symmetry and K value.

1,2-Bis-(1-{3-pyridyl-}3-methyltriazen-3-yl)ethane: Synthesis and X-ray crystal structure

3-Aminopyridine is diazotized in the conventional manner and the diazonium salt coupled with N,N ′-dimethylethylenediamine to afford the title compound (1), which is a potential antitumour agent. The compound has been characterized by spectroscopic methods. The 1H NMR spectrum shows evidence of rotational conformerism, from the observation of broadening of the N-methyl signals in the room-temperature spectrum. Low-temperature NMR spectra (down to 223 K) show the presence of three distinct rotamers. The crystal structure of 1,2-bis-(1-{3-pyridyl-}3-methyltriazen-3-yl)ethane (1) has been determined by single crystal X-ray diffraction analysis. The bis-triazene (1) exists as the "staggered" conformation in the solid state, with an "anti–anti" configuration around the N—N bond of the triazene units. The crystal structure of 1 is compared with the closely related bis-triazene 2 and also compared with the simple mono-triazene 3. Crystal data for 1, C14H18N8: orthorhombic, space group Pbca, a = 11.2550(8) Å, b = 8.8507(6) Å, c = 15.0069(10) Å, β = 90°, and V = 1494.91(18) Å3, for Z = 4.Key words: triazene, bis-triazene, pyridine, X-ray, VT NMR, diazonium coupling.

The Room Temperature Dielectric Spectrum of 2,2-Dimethyl-1 -butanol

The dielectric spectrum of the title substance ('neohexanol') in its pure liquid state is reported for 293 K up to 71 GHz and, for a restricted frequency range, also for lower temperatures (down to 253 K). The room temperature spectrum resembles that of alicyclic alcohols, in particular cyclopentanol, with respect to spectral shape, main relaxation time and the relation of the latter to viscosity, which similarity may be connected with the fact that these alcohols are able to form 'plastic crystals'.

Assignment for the Infrared Spectrum of Solid Sodium Propionate from Low-Temperature Measurements in Combination with 13C Isotopic Shifts

The infrared spectra of CH3CH2COONa and its 13C-labeled modifications (1-13C, 2-13C, and 3-13C) suspended in KBr disks were measured in the region 4000 -200 cm-1 at room temperature and liquid nitrogen temperature. Overlapping complex band contours appeared in some regions of the room temperature spectrum, most notably in the region 1500 -1350 cm-1, where 5 fundamentals having contributions from the methyl deformation, methylene bending, and carboxylate stretching modes should occur. In contrast to this, excellent resolution was reached at the low temperature, from which all 22 fundamentals expected in the whole spectral region investigated were detected. A complete assignment of the fundamentals is proposed mainly on the basis of the characteristic isotopic shifts of the three 13C substituted sodium propionate species. A fair number of the fundamentals were found to feature coupled modes having contributions from several group vibrations.

The temperature dependence of the 8920 Å band of NO2 and the location of the 000–000 band of the transition

The absorption spectrum of NO2 cooled to −30 °C has been photographed at high dispersion in the wavelength region 8200–9100 Å. Comparison with the room temperature spectrum shows that weak absorption from the ground state of the molecule underlies slightly stronger 'hot' band absorption at 8920 Å. Franck–Condon calculations based on the relative intensities of absorption bands from the 000 and 010 vibrational levels of the molecule indicate that the 000–000 band of the [Formula: see text] electronic transition lies near 10250 Å (1.21 eV) with a possible uncertainty of one quantum of ν2′ (0.09 eV). This result is in good agreement with the multiconfiguration SCF calculations of Gillispie and Khan (which are at variance with previous experimental deductions on the location of the 000–000 band).Some new assignments have been made in the rotational structure of the 8360 Å band.

Binding of Copper(II) to Proteins of the Photosynthetic Membrane and its Correlation with Inhibition of Electron Transport in Class II Chloroplasts of Spinach

Incubation of class II chloroplasts of spinach with copper in the light at pH = 8 in concentrations that inhibit oxygen evolution results in the formation of a copper (II) protein complex with the photosynthetic membrane. The EPR spectra indicate that the four nearest ligands to Cu(II) consist of three oxygen atoms and one nitrogen atom. The copper (II) protein appears to be pre­ dominantly associated with photosystem II. The formation of this protein as measured by the EPR signal amplitude of its room temperature spectrum correlates with the inhibition of oxygen evolution and of electron transport within photosystem I. This result indicates that the inhibition of photosynthetic electron transport by copper may be due to the formation of a copper (II) chelate with a membrane protein.