Theoretical study of the HeN2+ 2 dication

The structure and stability of the helio nitrogen molecular dication, HeN²⁺ ₂, is investigated by means of standard quantum chemical methods based on both single-reference and multi-reference formalisms. Sequences of correlation consistent basis sets are employed to establish convergence with respect to the size and the quality of the single-particle basis set. MRCI and CASPT2 calculations are reported for the HeN²⁺ ₂ ground-state ion which is found to be metastable. The barrier for the transition state of the reaction HeN²⁺ ₂→ N⁺ …NHe⁺ → N⁺ + NHe⁺ is calculated to be 59.5 kcals mol^?1. The structure of the transition state NHeN²⁺ was also determined from calculations using the MRCI and CASPT2 methods.     

An emission spectrum of InCl+

A spectrum, found in the 360- to 420-nm region following hollow-cathode excitation of InCl₃/In/He mixtures has been attributed to the InCl⁺ ion. Sixteen bands have been classified for the system which has been identified through rotational analysis to be B²Σ-X²Σ, consistent with photoelectron observations by Berkowitz and Dehmer. A second, very much weaker set of bands has been observed between 320 and 335 nm under the same experimental conditions. These latter bands constitute either a new system of InCl or a second InCl⁺ system.     

Theoretical study of the helio hydrogen cyanide dication HeCNH2+

The structure and stability of the helio hydrogen cyanide molecular ion, HeCNH²⁺, is investigated by standard quantum chemical methods. Single reference calculations are carried out using second-order perturbation theory (MP2), the coupled cluster expansion in the CCSD approximation, and the hybrid approach using a perturbative estimate of the triple excitation energy component designated CCSD(T). Multireference calculations using a complete active space (CASSCF) and a second-order perturbation theory estimate of correlation effects (CASPT2) are reported.     

The A2Π-X2Σ+ emission spectrum of zinc deuteride

The A²Π-X²Σ⁺ emission of ZnD was studied at moderate and high resolution in the region 346–505 nm. A detailed rotational analysis of 10 bands has been performed using the ²Π formulas of Mulliken and Christy, with the Almy and Horsfall centrifugal distortion term. The principal molecular constants for the X²Σ⁺ state are (cm^?1): B_e = 3.3990, α_e = 0.0964, D_e = 1.16 × 10^?4, β_e = 6.4 × 10^?6, γ₀ = 0.122, ω_e = 1141.54, ω_ex_e = 24.29, and, for the A²Π state, T_e = 23 280.55, B_e = 3.7772, α_e = 0.0868, D_e = 1.14 × 10^?4, A₀ = 343.29, p₀ = 0.149, q₀ = 1.53 × 10^?3, ω_e = 1361.49, and ω_ex_e = 20.69. RKR potential curves and A-X Franck-Condon factors were calculated. A comparison was made with the spectrum of ZnH and the isotopic splitting for ⁶⁴ZnD, ⁶⁶ZnD, and ⁶⁸ZnD is briefly discussed.     

Optical absorption spectrum of Ni2+ doped in ammonium zinc sulphate

The optical absorption spectrum of Ni²⁺ ion doped in ammonium zinc sulphate has been studied at room and liquid air temperatures. From the nature and the positions of the bands a successful interpretation of all the bands could be made assumingO _h symmetry for the Ni²⁺ ion in the crystal. The fine splitting of the³ T ₁ ¹ band at liquid air temperature has been successfully interpreted to be due to spin-orbit interaction. The crystal field and spin-orbit parameters derived areDq=1000 cm⁻¹;B=750 cm⁻¹;C=3.45B andξ=600 cm⁻¹.     

Optical absorption spectrum of Ni2+ ion doped in synthetic lecontite

The optical absorption spectrum of Ni²⁺ ion doped in lecontite (sodium ammonium sulphate dihydrate) single crystal has been studied at room and liquid air temperatures. All the bands could be assigned assumingO _h symmetry for the Ni²⁺ ion in the crystal. The splitting of³ T _1g (F) band at liquid air temperature has been attributed to spin-orbit interaction. The crystal field and spin-orbit parameters derived areD _q=1000 cm^?1;B=740 cm^?1;C/B=4.27 and ζ=600 cm^?1. All the bands observed show a blue shift when the crystal was cooled to liquid air temperature.     

Optical absorption spectrum of Co2+ in ammonium perchlorate single crystal

Single crystals of cobalt — doped ammonium perchlorate were grown at room temperature. The electronic absorption bands observed at room and liquid air temperatures have been assigned transitions from the ground⁴T₁(F) state to the excited⁴T₂(F),⁴A₂(F),²T₁(G) and⁴T₁(P) states. The crystal parameters derived areDq=880 cm^–1,B=865 cm^–1 andC= 4·63B.The authors wish to express their thanks to the authorities of the Indian Institute of Science, Bangalore for kind permission to use their spectrophotometer. Two of the authors (B. C. V.Reddy and J. L.Rao) express their greatful thanks to the council of scientific and Industrial Research (New Delhi) for financial assistance.     

Optical emission spectrum of rubidium atoms isolated in solid krypton

Saturation induced minima of the output power of a He/Ne-laser appear if Zeeman splitting equals the frequency separation. These minima have been investigated as a function of pressure. The results show pressure broadening caused by velocity changing and alignment destroying collisions. In contrast to Lamb-dip measurements the effect of phase changing collisions on collision broadening is negligible.     

The emission spectrum of CCl+

The emission bands, first observed by R. F. Barrow, G. Drummond, and S. Walker (Proc. Phys. Soc.A67, 186–187 (1954)) in a discharge through CCl₄, have been rotationally analyzed and found to be due to the A¹Π-X¹Σ⁺ transition of CCl⁺.     

Optical absorption spectrum of VO2+ in calcium tartrate tetrahydrate

Single srystals of calcium tartrate doped with VO²⁺ are grown from silica gel. Its optical absorption spectrum is studied at laboratory and liquid air temperatures. The spectrum is analysed and ascribed to VO²⁺ ion in C_4v symmetry. The following crystal field parameters are evaluated.

$\text{Dq = 1835}\text{cm}{}^{\mathrm{?1}}\text{, Ds = ?1980}\text{cm}{}^{\mathrm{?1}}\text{, Dt = 1280}\text{cm}{}^{\mathrm{?1}}$

     

Optical absorption and emission from irradiated RbMgF3:Eu2+ and KMgF3:Eu2+

The optical properties of irradiated RbMgF₃:Eu²⁺ and KMgF₃:Eu²⁺ have been investigated. Previous research has shown that Eu²⁺ ions in unirradiated RbMgF₃ give rise to broad band absorption around 250 nm and sharp intense line emission at 360 nm. When this material is irradiated little or no change occurs in the 250 nm absorption, but the lifetime of the Eu²⁺ 360 nm transition is reduced. In addition, new emission is observed at 680 nm. In the case of irradiated KMgF₃:Eu²⁺ two new emission bands are observed at 600 and 800 nm. All of these transitions have short lifetimes and are not due to Eu³⁺ ions.     

Optical absorption spectrum of Ni2+ ions doped in sodium potassium sulphate single crystal

Single crystals of nickel-doped sodium potassium sulphate were grown by slow evaporation method at room temperature. From the nature and position of the bands observed, a successful interpretation of all the observed bands could be made assuming the octahedral symmetry for the Ni^{2 +} ion in the crystal. The bands have been ascribed to transitions from the ground³A_2g(F) state to the excited³T_2g(F),¹E_g(D),³T_1g(F),¹T_2g(D) and³T_1g(P) states. The experimental and calculated energies are in good agreement. The crystal field parameters derived areDq= =880 cm^–1,B= 900cm^–1 andC=3600 cm^–1.One of the authors, Sujatha John expresses her thanks to the Secretary and the Principal, R. B. V. R. Reddy College, Hyderabad for according her permission to pursue the M. Phil. course.     

Optical absorption spectrum of Cr3+ in natural ruby

Two sharp line-like bands calledN andR lines on the red side, a close doublet (B lines) on the violet side and two broad bands are observed for natural ruby. At liquid air temperature the splitting ofR line was found and also three sharp-bands calledR, R′ andB lines are identified with spin-forbidden transitions of² E,² T ₁ and² T ₂. The two broad bands calledU band andY band are assigned accordingly to the spin-allowed transitions⁴ T ₂ and⁴ T ₁ respectively. The observed bands of natural ruby have been attributed to Cr³⁺ ion in an octahedral environment with trigonal distortion. The crystal field parameters which gave a good fit to the observed band positions areB=732 cm⁻¹,C=4.25B,Dq=1830 cm⁻¹,V=−1996 cm⁻¹ andλ=34 cm⁻¹.     

Matrix isolation spectrum of the 2491 Å system of NO2

The absorption spectrum of the 2491 Å NO₂ bands (${}^2\text{B}{}_2\text{←}\text{X}\text{?}{}^2\text{A}{}_1$) has been observed in neon and argon matrices at 6 K. Evidence for two distinct matrix sites is confirmed by the doubling of the electronic origin. The bands are shifted slightly to the blue (～ + 60 cm^?1) in neon and to the red (～ ?64 cm^?1) in argon. The excited state vibrational frequencies are reported.     

Effect of charge compensation on emission spectrum of Ca2SiO4:Dy3+ phosphor

The Ca2SiO4:Dy3+ phosphor was synthesized by the high temperature solid-state reaction method in air.The emission spectrum of Ca2SiO4:Dy3+ phosphor shows several bands at 486, 575, and 665 nm under the 365-nm excitation. The effects of Li+, Na+, and K+ on the emission spectrum of Ca2SiO4:Dy3a+ phosphor were studied. The results show that the emission spectrum intensity is greatly influenced by Li+, Na+,and K+. The charge compensation concentration corresponding to the maximum emission intensity is different with different charge compensations.     

Effects of inert gases on the degenerate four-wave-mixing spectrum of NO2

We describe the effects of He, Ar and N₂ on the resonant degenerate four-wave-mixing spectrum of NO₂. We report results obtained using the phase-conjugate and forward-geometry experimental configurations for various laser intensities and bandwidths. We find that the effect of buffer-gas pressure on the reflectivity of the laser-induced grating depends critically on the relative value of the laser intensityI to the saturation parameterI _sat. WhenI I _sat the four-wave-mixing signal initially decreases with increasing buffer-gas pressure. However, at pressures above ca. 100 Torr the signal increases. WhenI I _sat the signal is found to increase with buffer-gas pressure even at the lowest pressures studied. These observations do not agree with the standard model of degenerate four-wave mixing in the gas phase. We have investigated the source of these effects by employing different polarisation geometries of the pump and probe laser fields, and conclude that thermal gratings are responsible for the increase in signal observed at high buffer-gas pressure. This conclusion is supported by a simple gas kinetic model.     

基于太阳光谱的NO2浓度反演方法

 构建了一套光谱测量系统,以太阳光为光源,利用高精度成像光谱仪采集太阳光谱,选取某一时刻的太阳光谱为参考,结合当时的污染气体浓度数据,应用差分吸收原理,反演出其他任意时刻的NO2浓度。运用Origin7.5软件进行光谱解析,根据HITRAN数据库绘制吸收截面谱,并获取指定数值的应用,实现了对光谱谱线的定量分析,并且误差小。该反演过程具有光谱处理失真低以及反演参量精度高的特点,一定程度上提高了太阳光谱反演气体浓度的精度。实验结果与其他设备测量结果一致,证实了该方法的可行性。