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).     

The absorption spectrum of 12C2H2 between 12800 and 18500cm−1 II. Rotational analysis

The rotational structure of the vibrational bands of ¹²C₂H₂ is investigated in three spectral energy regions not previously systematically explored at high resolution, 12800–13500 cm^?1, 14000–15200 cm^?1 and 16500–18360 cm^?1, on the basis of new spectral data recorded by intracavity laser absorption spectroscopy. The rotational analysis of 17 new absorption bands arising from the ground state is reported (11 Σ_u ⁺ ? Σ_g ⁺ bands and 6Π_u ? Σ_g ⁺ bands). Four bands in the range studied show strong perturbations affecting both the line positions and intensities. Their detailed analysis is performed in order to determine the nature of the coupling schemes, the vibrational species and the rotational constants of the perturber states. Altogether, the vibration-rotation parameters of 21 newly observed vibrational states are derived.     

Laser-excited phosphorescence spectrum of C3S2 in an Ar matrix

The phosphorescence spectrum of C₃S₂ was observed in a low-temperature Ar matrix with excitation of an Ar⁺ laser. The spectrum consists of a very strong 0-0 band at 18 287 cm^?1 and well-resolved progressions in the ν₂, ν₅, ν₆, and ν₇ vibrations. Side bands were found on the high-energy sides of some transitions. The separation between the main and side bands is 23 cm^?1. Polarization analysis suggests that C₃S₂ is linear symmetric in the Phosphorescent state as in the ground electronic state. On the basis of symmetry considerations and a qualitative evaluation of spin-orbit coupling, the phosphorescent state is assigned to ³Σ_u^? with Σ_u⁺ and Π_u components split by spin-spin interaction. The Σ_u⁺ level is lower than the Π_u one by 23 cm^?1 and the main and side band emissions start from the Σ_u⁺ and Π_u levels, respectively. The Σ_u⁺ component seems to acquire allowed character from a ¹Σ_u⁺ state by spin-orbit coupling and from bent ${}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{?}}\text{(}{}^1\text{B}{}_2\text{)}$ and ${}^1\text{Δ}{}_{\mathrm{g}}\text{(}{}^1\text{A}{}_1\text{+}{}^1\text{B}{}_2\text{)}$ states by ν₅ vibronic coupling. Mixing of the Σ_u⁺ and Π_u components through ν₅ is responsible for most of the side bands. The ν₅ frequency is estimated to be 160 ± 20 cm^?1 in the ³Σ_u^? state from the intensities of ν₅ progression bands and from the ground-state frequency, 411 cm^?1.     

The 290-nm absorption system of propiolyl fluoride

The vapor-phase absorption spectrum of propiolyl fluoride HCCCOF and deuterio-propiolyl fluoride has been examined under medium resolution in the region from 303 to 260 nm. While considerable vibrational structure is evident, all bands are found to be rotationally diffuse. The electronic transition is identified as the singlet-singlet $\text{π}{}^1\text{← n}$ transition analogous to the 382-nm system of propynal. The evidence for a nonplanar excited-state geometry is discussed. The principal excited-state vibrational frequencies identified are 158 (ν′₉), 396 (ν′₈), and 1222 cm^?1 (ν′₃) for HCCCOF. The corresponding values for DCCCOF are 150, 390, and 1217 cm^?1, respectively. The triplet ← singlet system involving the same electron promotion has not been found.     

Anharmonic resonance interactions in the bending manifold associated with ν3 in 13C2D2 studied by high—resolution infrared and Raman spectroscopy

The Q branch of the 2ν₂ ← ν₂ band of ¹³C₂D₂ has been recorded with an instrumental resolution of about 0.003 cm^?1 using inverse Raman spectroscopy combined with stimulated Raman pumping in order to populate the ν₂=1 state. A weak local perturbation evident in the spectrum has been attributed to the effect of an anharmonic resonance between the ν₂=2 and ν₃=ν₄=ν₅=1 Σ⁺ _g, states. To study this interaction, the components of the latter vibrational manifold (Σ⁺ _g, ^? _g and Δ_g), together with all the bending states up to (ν₄ + ν₅)=2 associated with ν₃=1, have been characterized through the analysis of their infrared spectra. Both cold and hot bands from states thermally populated at room temperature, ν₄, ν₅, 2ν₄, 2ν₅ and ν₄ + ν₅, have been recorded in the region between 2300 and 3000 cm^?1 at an effective resolution of about 0.009 cm^?1. A simultaneous analysis of all the assigned transitions has been performed on the basis of a theoretical model which takes into account the rotational and vibrational ?-type resonances within each vibrational manifold, the Darling-Dennison anharmonic resonance between the ν₃ + 2ν₄ and ν₃ + 2ν₅ states, and the anharmonic interaction between the 2ν₂ and ν₃ + ν₄ + ν₅ states.     

High-K band structures in 164Er

High-spin states of the doubly-odd ¹¹²Sb were studied by in-beam spectroscopy using the ⁸⁸Sr (²⁸Si, p3n) and ⁸⁹Y (²⁹Si, α2n) fusion-evaporation reactions at beam energies of 120 and 108 MeV, respectively. γ?γ, charged particle-γ?γ coincidences, and γ?γ angular correlation analyses were employed for determining the level scheme of ¹¹²Sb. In the present work, all the levels except for low-lying states in ¹¹²Sb were newly established. Two ΔI = 1 strongly coupled bands were observed; one is a negative-parity band that is similar to those observed in the neighboring doubly-odd Sb isotopes and the other is a positive-parity band that has a new type structure not observed in the other isotopes. From the similarity of the properties of these ΔI = 1 bands to the bands built on 9/2⁺ 2p?1h states in the odd-A Sb isotopes, we suggest that these two ΔI = 1 bands should be associated with the [π(g_9/2)^?1 ? νh_11/2] and [π(g_9/2)^?1νg_7/2] configurations, respectively.     

High-resolution stimulated Raman gain spectrum of the ν1 band of SF6

We report rotationally resolved stimulated Raman gain spectra of the ν₁ band of SF₆. The fundamental band exhibits a rigid-rotor type spectrum that is readily fit with a band origin of Δα = 774.5445 and a single rotational term Δβ = ?1.10376 × 10^?4 cm^?1. We also observed and analyzed the ν₁ + ν₆ hotband with band origin at 774.1820 cm^?1. With an experimental resolution of 0.0024 cm^?1 there is no evidence for centrifugal distortion or tensor splitting in either band, although the ν₁ + ν₆ band does exhibit first-order Coriolis splitting as expected.     

The perpendicular band ν14 of benzene near 10 μm

The perpendicular band of the E_1u vibration ν₁₄ of C₆H₆, with band origin at 1038.2670 cm^?1, was measured on a Bomem high-resolution Fourier transform spectrometer with a 246-cm optical path difference. The spectrum was deconvolved to an effective linewidth of ～0.002 cm^?1. A total of 135 subbands have been assigned in the ν₁₄ band. The band was found to be remarkably free of perturbations by other states. A Hamiltonian matrix of order 2, including merely the rotational l-type resonances between the ν₁₄⁺(J, K) and ν₁₄^?(J, K ? 2) levels, was used for the treatment of the upper states of this band. A set of accurate spectroscopic constants was obtained, which reproduces a total of 3258 measured lines with an over-all standard deviation of 0.0006 cm^?1.     

Analysis of the ν9 and ν10 bands of cyclopropane

The infrared spectrum of gaseous cyclopropane has been measured in the regions 980–1080 and 1400–1500 cm^?1, containing the ν₁₀ and ν₉E′ fundamental bands, respectively, using a high-resolution Fourier transform instrument. Deconvolution was used to enhance the resolution in the crowded parts of the spectrum to ～0.0020–0.0025 cm^?1. Apart from the rotational l-resonance affecting mainly the low-K subbands, the ν₉ band is strongly perturbed by Fermi resonance with the 2ν₁₄² state lying ～41 cm^?1 above. The effects of the Fermi resonance are most pronounced in the high-KΔK = +1 subbands as the 2ν₁₄^?2 levels would cross the ν₉⁺ levels near K = 30. ^rR lines of 2ν₁₄^?2 for K = 24 to 36, enhanced by the resonance, have been identified in the region 1469–1475 cm^?1 of the spectrum. Two extra perturbation-enhanced subbands are found adjacent to the K = 16?17 and K = 17?16 subbands of ν₉: these have been ascribed to the K = 18?17 transitions in 2ν₁₄^?2 and to the K = 19?16 transitions in $\text{ν}{}_2\text{2ν}{}_{14}{}^0$, respectively, as their upper states coincide with the corresponding levels ν₉^?(K = 16) and ν₉⁺(K = 17). A combination of l-resonance and Fermi resonance is mainly responsible for the interactions causing the perturbations and appearance of the extra subbands, but a direct rotational interaction 〈ν₉^?(K)|h₃|2ν₁₄^?2(K + 2)〉 also had to be introduced to accurately account for the observations. In contrast, the ν₁₀ band is not appreciably perturbed by other states and merely exhibits effects of strong l-resonance in the low-K subbands, and K-doubling of the high-J lines of the K = 2–3 subband. A detailed analysis of the spectrum and of the perturbations is described and sets of accurate spectroscopic constants are reported for ν₁₀ and ν₉ as well as for the perturbing state 2ν₁₄², which reproduce 3020 observed lines of the ν₁₀ band with a standard deviation of 0.0008 cm^?1 and 1810 lines of ν₉ with a standard deviation of 0.0010 cm^?1.     

Analysis of the ν9ν10 band system of allene

The infrared spectrum of allene has been recorded with high resolution (0.002-0.004 cm^?1) on a Fourier transform instrument in the region 730 to 1170 cm^?1 containing the perpendicular bands, ν₉ and ν₁₀. A total of 21 subbands with KΔK ranging from ?6 to +14 have been assigned in the ν₉ band, and 26 subbands with KΔK = ?10 to +15 have been assigned in the ν₁₀ band. The bands are affected by a combination of a J_z-Coriolis and a quartic anharmonic interaction between their upper states ν₉ and ν₁₀. In addition, several other more localized perturbations are found in the spectrum. The nature of the interactions responsible for these perturbations is discussed, and five of the strongest perturbations are quantitatively accounted for by constructing a Hamiltonian matrix which includes five different perturbing states and their Coriolis and anharmonic resonances with the ν₉ and ν₁₀ upper states. A set of spectroscopic constants for the ν₉ and ν₁₀ states and for some of the perturbing states is reported.     

On theβ − decay of the 2s isomer in98Y and the existence of an intruder band in98Zr

The γ radiation from the ß^? decay of the high-spin isomer in⁹⁸Y has been studied at the separator JOSEF. A main goal was to get insight into the spins of levels in⁹⁸Zr which have been interpreted as members of an intruder band based on the 0₂ ⁺ state at 854 keV. The measuredγ-γ angular-correlations lead to the assignment of spins of 4 and 3 ? to the 2491 and 1844 keV levels, respectively, and contradict their interpretation as the 6⁺ and 4⁺ states of the proposed band. For the 2.0s isomer of⁹⁸Y, the ß{?}-decay properties suggest I=5 with a major configuration [πg_9/2,νs_1/2(g² _7/2)₀].     

Investigation of N 2 + (C 2Σ u + → X 2Σ g + fluorescence excited through auger decay of the 1s −1π* resonance

A theoretical investigation of N ₂ ⁺ (C ²Σ _u ⁺ → X ²Σ _g ⁺ molecular fluorescence excited through the Auger decay of the 1s ^?1π* resonance is carried out. The fluorescence cross sections are calculated with due regard for the dependence of the matrix element of the C → X dipole transition on the internuclear distance, the interference between channels of excitation via different vibrational levels v _r of the 1s ^?1π* resonance, the rotational structure of the fluorescence band, and the predissociation of the N ₂ ⁺ C ²Σ _u ⁺ v′ ≥3) states. The calculated cross sections are in good agreement with the experimental results of recent measurements. The results of the calculations have demonstrated that the observed dependence of the cross section of the (C ²Σ _u ⁺ (v′) → X ²Σ _g ⁺ (v″) fluorescence on the excitation energy and the fluorescence wavelength for a group of bands with equal values of the difference Δv = v′ ? v″ is associated with transitions between the vibrational levels of the electronic states involved in the excitation and subsequent cascade decay of the 1s ^?1π* resonance: N₂ (v ₀ = 0) → N*₂(1s ^?1π*(v _r)) ? N ₂ ⁺ : (C ²Σ _u ⁺ (v′) → X ²Σ _g ⁺ (v″).     

Nuclearg-factors of theJ π=21/2+isomer in112In and theJ π=6+ 112Sn

Theg-factor of theJ ^π=21/2⁺ isomeric state in¹¹¹In (T _1/2=13.3 ns) and of theJ ^π=6⁺ isomeric state in¹¹²Sn (T _1/2=13.7 ns) were measured using the spin rotation method. The result obtained for theJ ^π=21/2⁺ level in¹¹¹In,g=+0.47 (2), indicates that this state has an almost pure ((πg _9/2)^?1 νg _7/2 νd _5/2) shell model configuration. The experimental valueg=+0.04 (3) for theJ ^π=6⁺ isomer in¹¹²Sn agrees with the theoretical value calculated within the frame of the BCS model.     

High spin states in121Te

High spin states of¹²¹Te, populated in the¹¹⁴Cd(¹¹B,p3n) reaction, have been studied throughγ-ray spectroscopy. The level scheme has been established up toJ ^π=51/2^?. Three-quasiparticle states, based on the πg _7/2 ²?νh _11/2 andπg _7/2 d _5/2?νh _11/2 configurations, have been identified. A favoured 39/2^? state is suggested to be the fully aligned [πg _7/2 ²]₆₊?[νh _11/2 ³ _27/2? yrast non-collective oblate configuration. This assignment is supported by Total Routhian Surface (TRS) calculations which also suggest a similar oblate assignment to the states atJ ^π=21/2^? and 23/2^?. A higher 47/2^? state is also found and is suggested to be the fully aligned [πg _7/2 ²]₆₊?[νh _11/2 ⁵]_35/2? configuration.     

Infrared diode-laser spectrum of the CH3CN ν2 band: Analysis of local resonances with ν6±1 + 2ν8±2, ν4 + ν7±1 + ν8±1, ν4 + ν6±1, ν4 + ν7±1, and 2ν70 + ν8±1 states

Fifty-one sections of infrared diode-laser spectra of acetonitrile have been measured in the region from 2283.5 to 2235.7 cm^?1. About 450 transitions belonging to the ν₂ band have been assigned for K ≦ 7 and J ≦ 44. Anomalies found in the rotational structure have been proven to be due to five local resonances. Observed transition frequencies have been fitted by a least-squares method to a model which includes Fermi-type resonances (Δk = 0, Δ? = ± 3n) with ν₆^±1 + 2ν₈^±2 and ν₄ + ν₇^±1 + ν₈^±1 states, x, y-type Coriolis resonances (Δk = ±1, Δ? = ?3n ± 1) with ν₄ + ν₆^±1 and ν₄ + ν₇^±1 + ν₈^±1 states, and a centrifugal-distortion-type resonance (Δk = ±2, Δ? = ?3n ± 2) with a 2ν₇⁰ + ν₈^±1 state. The 11 × 11 dimensional energy matrix has been diagonalized in order to obtain the perturbed energy levels. The standard deviation for the fit is 1.075 × 10^?3 cm^?1. The molecular constants determined are also listed.     

Low-lying four-quasiparticle state in82Rb

The g-factor of the 6⁺ 191.3 keV excited state with a half-life T_1/2=12.3(6) ns in⁸²Rb populated in the⁷⁹Br(⁴He,n) and⁸¹Rb(³He,2n) reactions has been measured by the TDPAD method. On the basis of the experimental g-factor g _exp =+0.670(8) the four-quasiparticle configuration [πg9/2?ν(g9/2) ₇ ^2/3 ]₆₊ involving an anomalous neutron coupling has been assigned to this state.     

The[g 9 2/2 ]8+ state in96Zr

An 8⁺ state has been identified at 4390 keV in the doubly semi-magic nucleus⁹⁶Zr through the study of angular correlations among the γ radiation which is emitted in the β^? decay of the 10 s isomer of⁹⁶Y. This state probably has the configuration πg ₉ ^2/2 and is populated through a GT decay from the 8⁺ member of the [πg_9/2?νg_7/2] multiplet in⁹⁶Y. The deexcitation indicates that it belongs to a band based on the 0⁺ state in⁹⁶Zr.     

Absolute Line Intensities in Acetylene: The 1.5-μm Region

We measured 305 absolute line intensities in the ν₁+ν₃(Σ⁺_u)-0(Σ⁺_g) band of ¹²C₂H₂ and ¹³C¹²CH₂ and the ν₁+ν₂+(ν¹₄+ν⁻¹₅)⁰(Σ⁺_u)-0(Σ⁺_g), ν₁+ν₃+ν¹₄(Π_g)-ν¹₄(Π_g), and ν₁+ν₃+ν₅¹(Π_u)-ν₅¹(Π_u) bands of the main isotopomer, all observed near 1.5 μm. The absolute intensity of these bands are respectively 6.4882 (34), 0.12337 (10), 0.083746 (71), 0.58771 (28), and 0.32126 (11) cm⁻² atm⁻¹ at 296 K. In addition, we also determined Herman-Wallis factors for the first time in this spectral region.     

Signature splitting in two quasiparticle rotational bands of <Superscript>180,182</Superscript>Ta

The signature splittings in K^π = 1 ⁺: 7 /2[404] _π?9 /2[624] _ν, K^π = 0^?: 9 /2[514] _π?9 /2[624] _ν bands of ¹⁸⁰Ta and K^π = 0^?: 7 /2[404] _π?7 /2[503] _ν, K^π = 1^?: 5 /2[402] _π?3 /2[512] _ν, K^π = 1⁺: 7 /2[404] _π?9 /2[624] _ν bands of ¹⁸²Ta are analysed within the framework of two-quasiparticle rotor model. The phase as well as magnitude of the experimentally observed signature splitting in K^π = 1⁺ band of ¹⁸⁰Ta, which could not be explained in earlier calculations, is successfully reproduced. The conflict regarding placement of a 12 ⁺ level in K^π = 1 ⁺: 7 /2 ⁺[404] _π?9 /2 ⁺[624] _ν ground-state rotational band of ¹⁸⁰Ta is resolved and tentative nature of K^π = 0^?: 7 /2[404] _π?7 /2[503] _ν, K^π = 1⁺: 7 /2[404] _π?9 /2[624] _ν bands observed in ¹⁸²Ta is confirmed. As a future prediction for experimentalists, these two-quasiparticle structures observed in ¹⁸⁰Ta and ¹⁸²Ta are extended to higher spins.     

Microwave spectrum of monodeuterated diacetylene due to vibrationally induced dipole moment

Microwave spectrum of monodeuterated diacetylene (HCCCCD), which is nonpolar in the equilibrium configuration, was observed in various excited states of bending vibrations. Dipole moments in the ν₆, 2ν₆, and ν₆ + ν₉ vibrational states were determined from the Stark effect measurement to be 0.0907(6), 0.1681(14), and 0.0900(4) D with uncertainties in parentheses, where ν₆ and ν₉ denote respectively the CCH bending and lowest frequency bending vibrations. The l-type doubling constant in the ν₆ state is 2.1316(28) MHz. Rotational constants were determined in MHz; ν₆(Π), 4086.2165(44); 2ν₆(Δ), 4087.6963(58); ν₆ + ν₉(Δ), 4097.7537(50); 2ν₈(Δ), 4094.4786(103); ν₆ + ν₇(Δ), 4092.9074(176); ν₇ + ν₈(Δ), 4095.8925(354); 2ν₆ + ν₉(Φ), 4098.9505(339).