Laser Stark and laser-microwave double-resonance spectroscopy of the ν2 band of CD3I

The ν₂ fundamental band of CD₃I was investigated by means of the laser Stark spectroscopy using a 10.6 μm CO₂ laser and an N₂O laser as infrared radiation sources. The assignment was established for about 150 Stakr resonances. Laser-microwave double resonance was used to confirm the assignment. A least-squares analysis of the Stark spectrum gave the molecular constants: μ″ = 1.6504 ± 0.0004 D; μ′ = 1.6479 ± 0.0005 D; ν₀ = 28 461 093.8 ± 3.6 MHz; A′ - A″ = 234.0 ± 1.1 MHz; D_K′ - D_K″ = 0.121 ± 0.085 MHz. The uncertainties are 2.5 times the standard deviations. The single and the double primes refer to the ν₂ and the ground vibrational states, respectively.     

Laser Stark and laser microwave double-resonance spectroscopy of deuterated fluoroacetylene with the CO2 laser

The CO₂ laser Stark spectrum of deuterated fluoroacetylene was identified with the aid of the double-resonance technique for the ν₃, ν₃ + ν₅ ? ν₅, ν₃ + ν₄ ? ν₄, ν₃ + 2ν₅ ? 2ν₅, and ν₃ + ν₄ + ν₅ ? ν₄ ? ν₅ vibrational bands. Laser microwave double-resonance signals were observed in the presence of the Stark field. From the analysis of the double-resonance signals precise values of the dipole moment were obtained for 10 vibrational states, in Debye, with the uncertainties in parentheses: ground, 0.73292(22); ν₅, 0.75656(17); ν₄, 0.68412(24); 2ν₅(Σ⁺), 0.78063(21); ν₄ + ν₅(Σ⁺ or Σ^?), 0.70698(19); ν₃, 0.75772(30); ν₃ + ν₅, 0.78270(18); ν₃ + ν₄, 0.70822(17); ν₃ + 2ν₅(Σ⁺), 0.80808(25); ν₃ + ν₄ + ν₅(Σ⁺ or Σ^?), 0.73329(17). The band origins were determined (in cm^?1); ν₃, 1045.9242(8); ν₃ + ν₅ ? ν₅, 1049.6441(8); ν₃ + ν₄ ? ν₄, 1047.8700(8); ν₃ + 2ν₅ ? 2ν₅(Σ⁺-Σ⁺), 1053.0374(8); ν₃ + ν₄ + ν₅ ? ν₄ ? ν₅(Σ⁺?Σ⁺ or Σ^??Σ^?), 1051.5040(8).     

Infrared-microwave double-resonance probing of the population-depopulaton of rotational states in the NO2 molecule

A 10.6-μm CO₂ laser operating over a power range 5 ≤ p ≤ 135 watts was used to pump some select vibrational transitions in the NO₂ molecule while monitoring the rotational transitions (9_1,9 → 10_0,10), (23_2,22 → 24_2,23), and (40_2,38 → 39_3,37) in the (0, 0, 0) vibrational level and the (8_0,8 → 7_1,7) rotational transition in the (0, 1, 0) vibrational level. These rotational transitions were monitored by microwave probing to determine how the population of states in the rotational manifolds was being altered by the laser. Coincidences between some components of the ν₃-ν₂ band of NO₂ and the CO₂ infrared laser lines in the 10-μm region appeared to be responsible for the strong interaction between the continuous laser beams and the molecular states. Characteristic rate curves for population-depopulation changes in the chosen rotational levels listed above were found for various power levels from the laser pump. Rate coefficients for intensity decay for various laser powers were calculated from experimental data and are presented.     

Laser-radiofrequency double-resonance spectroscopy of methyl chloride: Hyperfine structure of the ground and ν6 states

Pure quadrupole resonances of methyl chloride have been observed using the highly sensitive method of infrared-radiofrequency double resonance inside a laser cavity. Quadrupole resonances have been observed for the ground and ν₆ states for both the CH₃Cl³⁵ and CH₃Cl³⁷ isotopes using the direct double-resonance as well as collisionally induced satellites. Most of the six hyperfine constants: the quadrupole coupling constant, eqQ; its rotational dependence, χ_J and χ_K; Hougen's coefficient, χ_D; and the spin-rotation constants, C_N and C_K, have been determined for the two states for both isotopes.     

Laser-radiofrequency double-resonance spectroscopy of formic acid: Assignment and analysis of the ν6 and ν8 bands

The highly sensitive method of infrered-radiofrequency double resonance inside a carbon dioxide laser cavity has been used to observe direct K-type doubling transitions in formic acid. Radiofrequency transitions corresponding to both ν₆ and ν₈ bands were observed. In the light of these new data some earlier infrared laser measurements are now assigned unambiguously. This results in greatly improved band parameters and a $\text{ν}{}_6\text{ν}{}_8$a-type Coriolis coupling constant that is 10 times better defined.     

Laser-microwave double-resonance spectroscopy in CF3I with four CO2-laser lines

Double-resonance effects produced by three CO₂-laser lines, the 9.4-μmR(12),R(14), and R(18), have been newly observed. From an analysis of the observed laser-induced changes in intensity of various microwave transitions, the infrared transitions which were accidentally coincident with these three laser lines were determined. In every case an exact rotational assignment of the infrared transition was possible, but in some cases the assignment of the vibrational band involved was difficult. When the previously discussed (l) effects produced by the R(16) laser line are included these four consecutive laser lines pump a total of seven infrared transitions of CF₃I. It appears that all seven transitions belong to different fundamental, combination, and hot bands.     

Laser-radiofrequency double-resonance spectroscopy of 13CH3I

Pure quadrupole resonances of the I¹²⁷ nucleus of ¹³CH₃I have been observed using laser-radiofrequency double resonance. Quadrupole coupling constants are reported for the ground, ν₃, 2ν₃, ν₆, 2ν₆, ν₃ + ν₆, and 2ν₃ + 2ν₆ states. Smaller hyperfine constants are also reported for the ground and ν₆ states.     

ESR OF Ni(C3H10N2)2NO2(ClO4) CRYSTAL

报道了Ni(C     

Cl nuclear quadrupole resonance studies of molecular motions of ClO3 and water diffusion in Ca(ClO3)2·2H2O

A ³⁵Cl nuclear quadrupole resonance (³⁵Cl-NQR) investigation of polycrystalline Ca(ClO₃)₂·2H₂O is described. The ³⁵Cl-NQR frequencies (ν_Q) for two resonance lines (ν_Q1 and ν_Q2), the spin lattice relaxation time (T_1Q) for ν_Q2 only and the line width δν_Q2 were measured in the temperature range 292–345 K, except for the frequency measured up to 455 K. The observed decrease in the resonance frequencies with increasing temperature permitted the determination of the frequencies of librations of the ClO₃⁻ ion about two axes perpendicular to the three-fold axis of the ion mainly responsible for this effect. The temperature dependence of the relaxation time T_1Q proved the occurrence of water diffusion and hindered rotation of ClO₃⁻ ions. The activation energies of these two molecular motions were determined, and their effect on the electric field gradient at the site of a chlorine nucleus was discussed. Temperature measurements of the line width δν_Q2 confirmed the conclusions drawn from the analysis of T_1Q(T).     

NO2分子的光学-光学双色双共振多光子离化谱

以Nd:YAG激光器的二倍频输出光为抽运光，其三倍频输出抽运的光学参量发生/放大器输出光为探测光，利用光学-光学双色双共振多光子离化光谱技术(OODR-MPI),获得了NO₂分子在605—675nm探测光波长范围内的多光子离化激发谱. 通过对NO₂分子离化机理的分析，确定了在此波长区间，NO₂分子经1+3+1双共振多光子过程离化，离化通道为NO₂(X²A₁)hν     

NO2分子的光学-光学双色双共振多光子离化谱

以Nd:YAG激光器的二倍频输出光为抽运光,其三倍频输出抽运的光学参量发生/放大器输出光为探测光,利用光学-光学双色双共振多光子离化光谱技术(OODR-MPI),获得了NO₂分子在605—675nm探测光波长范围内的多光子离化激发谱. 通过对NO₂分子离化机理的分析,确定了在此波长区间,NO₂分子经1+3+1双共振多光子过程离化,离化通道为NO₂(X²A₁)hν 关键词： 2')" href="#">NO₂ 光学-光学双共振多光子离化谱 里德伯态 分子常数     

Electron spin resonance investigation of the structural phase transitions in Alurea6(ClO4)3 and Ga urea6(ClO4)3

Second order structural phase transitions in Alur₆(ClO₄)₃ and Gaur₆(ClO₄)₃ with T_c ～ 300 K are studied by means of ESR on single crystals doped with the analogous Cr(III) compound. The transitions are antiferrodistortive and of the displacive type, the displacements resulting from the condensation of a X₂ mode $\text{(k = (0}\text{1}\text{2}\text{1}\text{2}\text{))}$ of the ClO₄ ions. The ESR parameters have the same temperature dependence as the order parameters and can be described by D and E～φ～. The space group describing the structure changes from S₆² to S₂¹, and the number of domains is multiplied by three. Above 300 K the crystals already consist of two domains, resulting from a ferrodistortive phase transition D_3d⁶ → S₆². The actual transition temperature of the latter phase transition lies at some temperature above the decomposition temperature of the crystals.     

Temperature evolution of the infrared spectrum of Ni(ClO4)2·6H2O

Temperature evolution of the infrared spectrum of the title compound confirms the phase transition temperatures 223, 311 and 355 K reported earlier and suggests a new phase transition at 180 K. From the spectral evidence, the transitions below the room temperature (～300 K) are attributed to tumbling motion of the metal aquo-complex, while those above the room temperature are attributed to reorientational motion of the water molecule. The space group in low temperature phases is suggested to be C²_s.     

Infrared-microwave double resonance of 12CH3OH with a CO2 laser

The Stark effect of the 2₂ ← 2₁(E₁), 2₁ ← 3₀(E₁) microwave transitions in the ground state and the 2₂ ← 2₁(E₁) microwave transition in the first excited CO stretching vibrational state are measured by means of infrared-microwave double resonance with the ^qQ₁(2)E₁ infrared transition as the pump transition in the range of 1000 to 2300 V/cm. The dipole moments μ_a and μ_b as well as the off-diagonal rotational constant D_ab are determined for both the ground and the excited states. The frequency of the ^qQ₁(2)E₁ infrared transition is found to be lower by 128 ± 2 MHz than that of the P(34) CO₂ laser.     

Specific heat of Ni(ClO4)26H2O between 2 and 17 K

A specific heat investigation of nickel perchlorate hexahydrate was performed between 2 and 17 K. Lattice vibration and magnetic contributions were separated. The lattice term obeys a Debye αT³ law, with $\text{α = 4.04 × 10}{}^{\mathrm{?3}}\text{J}\text{K}{}^4$ mol. The magnetic contribution comes from the splitting of the ground state triplet of the Ni²⁺ ions, by axial and rhombic crystal field distortions, which can be explained by a Schottky specific heat with D = 1.72 KandE = 0.06 K.     

Infrared-microwave double resonance as an aid in assignment of optically pumped submillimetre laser lines: CH2CF2, CH2F2, and CH3OH

Infrared-microwave double resonance has been used to confirm recent assignments of optically pumped submillimeter wave laser lines in CH₂CF₂ and CH₃OH, as well as a tentative assignment of a line in CF₂H₂. Intracavity double resonance signals have also been obtained in CF₂CH₂ using a circular copper waveguide laser.     

Opto-galvanic spectroscopy of some molecules in discharges: NH2, NO2, H2 and N2

The change of the discharge voltage when laser light crossing the discharge is tuned to a molecular transition has been measured. Experiments have been performed in the wavelength region between 570 nm and 620 nm with discharges in NH₃, NO₂, H₂, N₂, O₂ and argon. Transitions from the ground states of NH₂ and NO₂ and transitions from metastable states of N₂ and H₂ have been detected. The spacial dependence of the opto galvanic in a low pressure dc-discharge of H₂ and N₂ has been studied.     

Theory of the Zeeman effect in doublet states of a near-symmetric rotor: Application to the A2 ← B1 transition of ClO2

Matrix elements of the Hamiltonian for doublet states of rotating molecules in a Zeeman field are calculated in the uncoupled (J, S) representation. The energy matrix assumes a simple form for near-symmetric rotors, when the magnetic interactions are diagonal in K.     

Microwave spectrum of the HO2 radical

Rotational transitions of the HO₂ free radical, a type 1₀₁ ← 0₀₀, 2₀₂ ← 1₀₁, 2₁₂ ← 1₁₁, and 2₁₁ ← 1₁₀, and b type 6₁₆ ← 7₀₇, 7₁₇ ← 8₀₈, 9₀₉ ← 8₁₈, and 10_0,10 ← 9₁₉, have been observed up to 137 GHz with microwave spectroscopy. The rotational constants, the centrifugal distortion constants in the symmetric-top approximation, the spin-rotation coupling constants, and the coupling constants of Fermi contact and dipole-dipole interactions are determined accurately. The absolute value of ?_ab + ?_ba, the off-diagonal component of the spin-rotation interaction tensor, is obtained from its second-order perturbation contributions to the spin doublings of the b-type rotational transitions. The small value of the Fermi contact parameter leads to the conclusion that the hydroperoxyl radical is a π-electron radical. The lowest two K-type doubling transitions, which are of particular interest to radioastronomy, are predicted on the basis of the molecular constants obtained.     

Al2O3-Y2O3-ZrO2三相复合陶瓷的介电谱研究

采用传统的固相反应法,在1400–1500 ℃下烧结,制备得到Al₂O₃-Y₂O₃-ZrO₂三相复合陶瓷.样品的结构、形貌和电性能分别用X射线衍射(XRD)、扫描电子显微镜(SEM)及介电谱表征.XRD表明此三相复合体系无其他杂相,加入Y₂O₃及ZrO₂后使得Al₂O₃成瓷温度降低;SEM表明此体系晶粒直径为200–500 nm,并且样品随烧结温度的升高而变得更加致密,晶界更加清晰;介电损耗谱中出现峰值弛豫现象,根据Cole-Cole复阻抗谱得出其为非德拜弛豫. 关键词： 2O₃-Y₂O₃-ZrO₂三相陶瓷')" href="#">Al₂O₃-Y₂O₃-ZrO₂三相陶瓷 介电弛豫 阻抗谱 热导率