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A Fourier-transform microwave spectrum of the cis-β-cyanovinyl radical is re-measured for the Ka = 0 ladder of the a-type transitions up to 30 GHz and the 212–111 transition at 19.85 GHz.

The HOSO2 radical was detected by microwave spectroscopy in a discharge plasma of a SO2/H2O gas mixture. The observed spectrum shows tunneling splittings due to the OH torsional motion. A least-squares analysis considering interactions between the two torsional sublevels of the ground vibronic state, 0+ and 0−, reproduces the observed transition frequencies with a standard deviation of ca. 3 kHz. The splitting between the two torsional sublevels is accurately determined to be 24.3 MHz for HOSO2 and 0.08 MHz for DOSO2. The potential barrier for the OH torsional motion is estimated to be 1150 cm−1 from a one-dimensional hindered rotor model.

34 pags., 15 figs., 3 tabs., Carbonyl oxides, RRCOO, alternatively known as Criegee intermediates (CIs), are short-lived molecules produced from ozonolysis of alkenes. These ozonolysis reactions yield highly excited CIs, and most of them promptly decay with emission of the OH radical and other products. Some of the nascent CIs are stabilised by collisional relaxation with surrounding molecules, and react with atmospheric trace constituents, such as SO and gaseous organic compounds, converting them to more highly oxygenated molecules relevant to formation of aerosols. Hence, reactions of CIs are of central interest for atmospheric chemists. Physico-chemical properties of CIs are strongly related to their geometrical and electronic structures, which are often discussed based on spectroscopic information. Especially, very high resolution rotational spectroscopy provides critical information about molecular structures and intramolecular dynamics, and also enables us to probe individual isomers, conformers, and isotopologues, with complete selectivity. This article reviews the rotational investigations carried out on several CIs, their bimolecular complexes and primary reaction products, focusing on their molecular structure, conformational behaviour and reactivity., This research was supported by JSPS KAKENHI Grant Nos. 19205002 (Y.E.), 25410004 (M.N. and Y.E.) and 15K05378 (M.N.) and by the Ministry of Science and Technology of Taiwan under Grant Nos. MOST 104-2113-M-009-020 (Y.E.) and MOST 105-2811-M-009-026 and 106-2811-M-009- 023 (C.C.).

The 101–000 and 202–101 rotational transitions of a monohalomethylene, HCI, are observed in a discharge plasma of diiodomethane by Fourier-transform microwave (FTMW) and FTMW-microwave double-resonance spectroscopy. The effective rotational constant ( B + C ) / 2 , the centrifugal distortion constant Δ J , and the quadrupole coupling constant of the iodine nucleus are determined from the observed line frequencies. The nuclear spin-rotation coupling constant C bb is required to be included into the set of fitting parameters for a satisfactory analysis of the observed line frequencies.

Pure rotational transitions of cis-OSOO are identified in a discharge plasma of a SO2 and O2 gaseous mixture by Fourier-transform microwave (FTMW) and FTMW-MW double-resonance spectroscopy. Both a- and b-type transitions are observed for this molecule, and the rotational and centrifugal distortion constants are precisely determined from the observed line positions. The inertial defect calculated from the determined rotational constants indicates that the cis-OSOO molecule has a planar equilibrium geometry in the ground vibronic state.

Doppler-limited absorption spectra of dicarbon are recorded for Phillips bands ( A 1 Π u – X 1 Σ g + ) involving v ′ = 9 –11 at a room temperature. Small energy shifts of rotational levels are identified in the v = 10 level of the A 1 Π u state. The spin-orbit interaction between A 1 Π u ( v = 10 ) and c 3 Σ u + ( v = 7 ) is responsible for the level shifts. In addition to the perturbations in A 1 Π u ( v = 10 ) , those previously identified in the v = 2 and 6 levels of A 1 Π u are re-investigated. The magnitude of the spin-orbit interaction between the A 1 Π u and c 3 Σ u + states is evaluated to be approximately 4 cm−1 from perturbation analyses for these vibronic levels.

Measurement of pure rotational transitions for the vinylthio radical, CH2CHS, previously observed by Fourier-transform microwave spectroscopy (Nakajima et al., 2007), are extended to a number of fine and hyperfine component lines split by the unpaired electron spin and the three non-equivalent protons. All the measured transition frequencies have been analyzed by a Hamiltonian for doublet asymmetric top molecules with hyperfine interaction terms for three nuclear spins, yielding precise molecular constants of CH2CHS in the ground state. Discussions on the electronic structure of CH2CHS are given based on the determined molecular constants.

Pure rotational transitions of the anti-form of the simplest alkyl-substituted Criegee intermediate, anti-CH3CHOO, were observed by Fourier-transform microwave spectroscopy. The observed transition frequencies in the A and E levels of the ground vibrational state were analyzed together, and molecular constants including parameters which characterize the internal rotation of the methyl rotor were determined. The experimentally determined barrier height of the three-fold potential for the methyl internal rotation is 399.1 cm−1, less than a half of that of the other conformer, syn-CH3CHOO (Nakajima and Endo, 2014).

Pure rotational transitions of the simplest Criegee intermediate, CH2OO, were observed for several excited vibrational levels by Fourier-transform microwave spectroscopy combined with a double-resonance technique, and precise rotational constants of vibrationally excited CH2OO were determined. Comparing the experimentally determined vibration–rotation constants with those derived from a high-level ab initio potential energy surface, vibrational assignments were made for the observed levels. The observed intensities of the 101–000 rotational lines suggested that the COO bending mode is significantly excited.

Doppler-limited excitation spectra of the C2 anion were observed for the (2,4), (3,5), and (4,6) bands of the B 2 Σ u + – X 2 Σ g + system by laser-induced fluorescence spectroscopy at room temperature. Doublet peaks which are expected for rotational lines of a 2 Σ – 2 Σ transition were resolved in the spectra. The vibrational term values and molecular constants of the v = 4–6 levels in the X 2 Σ g + state were experimentally determined.

Excitation spectra of the d 3 Π g - c 3 Σ u + band system of the C2 molecule were observed at room temperature by laser-induced fluorescence spectroscopy. Molecular constants of the c 3 Σ u + state were determined for the v = 0, 1, 2, 3, and 5 levels, including the centrifugal distortion constant. A level crossing between the v = 1 level of the c 3 Σ u + state and the v = 7 level of the a3Πu state was unambiguously identified by simultaneously observing the 3–1 band of the d 3 Π g - c 3 Σ u + system and the 3–7 band of the Swan system. Rotational level shifts observed in these vibronic levels could be explained by the perturbations arising from the L±S∓ and J±L∓ terms of the spin-orbit and rotational Hamiltonians. De-perturbed molecular constants for the c 3 Σ u + ( v = 1 ) and a3Πu(v = 7) states are presented, and the possibility of an additional perturbation by another level, A1Πu(v = 2), is discussed.

Pure rotational transitions of the vinoxy radical in the ground vibronic state have been observed by Fourier-transform microwave spectroscopy in the cm-wave region and double resonance spectroscopy in the mm-wave region. Total of 6 rotational transitions are newly observed in the present work, which are least squares fitted together with the mm-wave data observed previously (Endo et al., 1985). The hyperfine coupling constants for the third proton in the –CHO moiety of the vinoxy radical have been determined precisely for the first time. Four b -type transitions, that escaped to be detected in the previous study in the mm-wave region, have provided a more accurate set of molecular constants for the ground vibronic state.

Pure rotational transitions of weakly bound complexes of the simplest Criegee intermediate CH2OO with Ar, CO, and N2 are observed by Fourier-transform microwave (FTMW) and FTMW-MW double-resonance spectroscopy. Many of the observed lines show doublet peaks associated with the tunneling splitting between the two equivalent configurations of the complexes. The intermolecular distances of the complexes are derived from the precise rotational constants determined in this study. The separations between two components of the doublet peaks observed for c-type transitions of CH2OO–Ar are satisfactorily demonstrated by a one-dimensional hindered rotor model for the internal rotation of the CH2OO monomer.

Electronic excitation spectra of the B 2 A ″ - X 2 A ″ transition of the trans-2-methylvinoxy radical were observed in the region of 29 000–32 000 cm−1 by laser-induced fluorescence and fluorescence depletion spectroscopy. Fourteen vibronic bands observed in the depletion spectrum were unambiguously identified to be originating from the radical. Dispersed fluorescence spectra from three different vibronic levels were also obtained, and a total of 69 emission bands were assigned, yielding the ground state vibrational constants.

Pure rotational transitions of the dimethyl-substituted Criegee intermediate (dimethyl carbonyl oxide, acetone oxide), (CH

Gas phase excitation and emission spectra of three naphthylmethyl radical chromophores are presented. These resonance-stabilized species, 1-naphthylmethyl, 2-naphthylmethyl, and α-acenaphthenyl, each possessing an sp(2) carbon adjacent to a naphthalene moiety, are studied by resonant two-color two-photon ionization, laser induced fluorescence, and dispersed fluorescence spectroscopy. Identification of the radicals is made through a combination of dispersed fluorescence and density functional theory calculations. All three species possess spectra in the 580 nm region. The possible relevance to unidentified spectroscopic features such as the diffuse interstellar bands and emission from the Red Rectangle nebula is discussed.

The electronic spectrum of the jet-cooled 1-indanyl radical has been identified in the products of a hydrocarbon discharge in argon. Electronic excitation spectra were observed in the region 20800-22600 cm(-1) by resonant two-color two-photon ionization and laser-induced fluorescence spectroscopies. In addition to the new spectrum at m/z = 117, the spectrum of 1-phenylpropargyl was also observed strongly, as was an unidentified spectrum carried by m/z = 133. The origin band of the 1-indanyl A2A''-X2A'' band system was observed at 21159 cm(-1) with the ionization potential of the radical experimentally determined to be 6.578 +/- 0.001 eV from a photoionization efficiency spectrum. Single vibronic level fluorescence was dispersed to determine the ground state vibrational frequencies that were utilized to confirm the identity of the radical in comparison with quantum chemical calculations. The calculated ground state frequencies and ionization potential, along with a calculated dispersed fluorescence spectrum of the origin band for the 1-indanyl radical, all provide a positive chemical identification.

The cis-1-vinylpropargyl (cis-1VPR, cis-pent-4-en-1-yn-3-yl) and trans-1-vinylpropargyl (trans-1VPR, trans-pent-4-en-1-yn-3-yl) radicals, produced in a supersonically cooled hydrocarbon discharge, have been identified by a synergy of 2-dimensional fluorescence and ionization spectroscopies, revealing their electronic origin transitions at 21,232 and 21,645 cm(-1) respectively. These assignments are supported by an excellent agreement between calculated ground state frequencies of cis-1VPR and trans-1VPR with those obtained by dispersed fluorescence spectroscopy. In addition, high-resolution rotational contours of the two bands are well simulated using calculated X- and A-state trans-1VPR and cis-1VPR rotational constants. Finally, computed origin transition energies of these two isomers are within several hundred wavenumbers of the observed band positions. With the 1-phenylpropargyl radical, the 1VPR isomers are the second 1-substituted propargyl species to have been observed abundantly from a hydrocarbon discharge, while no 3-substituted analogue has been positively identified. This is likely due to the greater resonance stabilization energy of the 1-substituted species, arising from concerted delocalization of the unpaired electron over the vinyl and propargyl moieties.

The rate constants for the reactions of C2(X1Sigma(g)+) with H2 and D2 have been investigated experimentally and theoretically to assess the statistical theory of the reaction and to reveal the mechanism of the reaction. The ground-state C2 radicals were generated by multiphoton laser-photolysis of C2Cl4 at 248 nm and were probed by a laser-induced fluorescence method using the Mulliken system (D1Sigma(u)+-X1Sigma(g)+). Rate constants have been measured to be k[C2(X)+H2] = 5.6 x 10(-11) exp[-9.1 (kJ mol(-1))/RT] and k[C2(X)+D2] = 3.2 x 10(-11) exp[-9.9 (kJ mol(-1))/RT] cm3 molecule(-1) s(-1) in the temperature range 293-395 K and at total pressure around 10 Torr (He buffer). Quantum chemical calculations at the MRCI level revealed that the reaction predominantly proceeds via a collinear direct-abstraction transition state. The measured rate constants as well as the kinetic isotope effect were well reproduced by the transition-state theory based on the MRCISD+Q/aug-cc-pV5Z calculations, provided that the anharmonic bending vibrations of the transition states were properly treated. The effect of the Davidson correction was found to be significant for the potential energy surface around the early transition state.

The gas-phase laser-induced fluorescence (LIF) spectrum of a 1-phenylpropargyl radical has been identified in the region 20,800-22,000 cm(-1) in a free jet. The radical was produced from discharges of hydrocarbons including benzene. Disregarding C2, C3, and CH, this radical appears as the most strongly fluorescing product in a visible wavelength two-dimensional fluorescence excitation-emission spectrum of a jet-cooled benzene discharge. The structure of the carrier was elucidated by measurement of a matching resonant two-color two-photon ionization spectrum at m/z = 115 and density functional theory. The assignment was proven conclusively by observation of the same excitation spectrum from a low-current discharge of 3-phenyl-1-propyne. The apparent great abundance of the 1-phenylpropargyl radical in discharges of benzene and, more importantly, 1-hexyne may further underpin the proposed importance of the propargyl radical in the formation of complex hydrocarbons in combustion and circumstellar environments.

A laser-induced fluorescence excitation spectrum of the cyclohexadienyl ( c -C 6 H 7 ) radical was observed in the region between 550 and 530 nm under jet-cooled conditions. A partly rotationally resolved spectrum of the vibronic origin band was obtained with a high-resolution laser scan. The observed rotational structure of the origin band is that of a b -type transition, being not discrepant with the A ∼ 2 A 2 – X ∼ 2 B 1 electronic transition which has been indicated by a few theoretical calculations. The origin band position and the rotational constants in the upper and lower states were determined from a rotational analysis of the spectrum. The determined molecular constants agreed very well with results of our ab initio calculations. The theoretical vibrational frequencies for the upper and lower electronic states were also calculated for comparison with the experimental results.

We observed microwave absorption spectra of some deuterated benzenes and accurately determined therotational constants of all H/D isotopomers in the ground vibrational state. Using synthetic analysis assuming that all bond angles are 120°, the mean bond lengths were obtained to be r[0](C–C) = 1.3971 Å and r[0](C–H) =r[0](C–D) = 1.0805 Å. It has been concluded that the effect of deuterium substitution on the molecular structureis negligibly small and that the mean bond lengths of C–H and C–D are identical unlike small aliphatic hydrocarbons, in which r[0](C–D) is about 5 mÅ shorter than r[0](C–H). It is considered that anharmonicity is very small in the C–H stretching vibration of aromatic hydrocarbons.

The Ã(2)Σ(+)-X̃(2)Πi band system of l-SiC3H in the region 14,700-16,300 cm(-1) was re-investigated by laser induced fluorescence (LIF) and fluorescence depletion spectroscopy. Rotational analyses were made for three intense bands 0(0)(0), 4(0)(1), and 6(0)(1)7(0)(1) by observing high-resolution LIF excitation spectra. The determined rotational constants demonstrate that SiC3H is linear in the à state, as is the case in the X̃ state, and the observed band types are consistent with the vibrational assignments. The ν3(″) (C1-C2 stretch) level was identified in a newly observed dispersed fluorescence spectrum from the zero-vibrational level of the à state.

In a discharged supersonic jet of a CS2 and C2H2 mixture, a vibronic band system of a new radical species was observed in the energy region 21 800–23 000 cm−1 by laser-induced fluorescence (LIF) spectroscopy. The LIF excitation spectrum shows progressions with 490 and 80 cm−1 separations. The vibronic structure of a dispersed fluorescence (DF) spectrum, obtained by tuning a probe laser to the vibronic origin band, also consists of progressions with 520 and 100 cm−1 separations. A high-resolution laser scan provided a rotationally resolved LIF excitation spectrum for the vibronic origin band, showing the rotational structure of a-type transitions of a near-prolate top. Several chemical tests indicate that the spectral carrier contains sulfur atom(s), one hydrogen atom and more than one carbon atoms. Electronic transition energy, vibrational frequencies, and rotational constants of this species are similar to those of SCCS− [M. Nakajima, Y. Yoneda, Y. Sumiyoshi, T. Nagata, Y. Endo, J. Chem. Phys. 119(2003)7805–7813.], and the spectral carrier was assigned as an isoelectronic radical, bent HSCCS. Ab initio geometrical optimizations supported the spectral carrier to be HSCCS. The observed electronic transition was assigned to be the B ∼ 2 A ″ – X ∼ 2 A ″ transition, which corresponds to the Π–Π transition in the limit of linear geometry. The observed vibrations in the excitation and DF spectra were assigned as the symmetric C S stretching (ν5) and SCC bending (ν7) modes by comparing the results of theoretical calculations.

Rotationally resolved fluorescence depletion spectra have been observed for the vibronic bands of the A ˜ 2 Π g – X ˜ 2 Π u system of SCCS − . The observed line widths varied from 0.03 to ∼2 cm −1 due to the lifetime broadening in the upper levels of the vibronic bands. The excited state lifetimes have been estimated from the spectral line widths, which show a distinct vibrational mode dependence.

In a discharged supersonic jet of carbon disulfide, a band system of a new species is observed by laser-induced fluorescence (LIF) spectroscopy. Rotationally resolved spectra show that the observed electronic transition is 2Π3/2–2Π3/2. Since both sulfur and carbon atoms have even numbers of electrons, it is concluded that the spectral carrier is an ionic species. Furthermore, the spectral carrier is confirmed to have two equivalent carbon atoms from the LIF spectra of the 13C-substituted species. With a help of ab initio calculations, the carrier is identified as the linear negative ion SCCS−, where the observed electronic transition is considered to be A 2Πg–X 2Πu. A mass spectrometric measurement also gives evidence that SCCS− is produced in the discharged jet. The vibrational structure for the upper electronic state is determined by both LIF and fluorescence depletion spectroscopy. A dispersed fluorescence spectrum is also observed to determine the vibrational structure of the lower electronic state. ...

Pure rotational transitions of the NCCS radical, showing resolved fine and hyperfine splittings, have been observed by Fourier-transform microwave spectroscopy in a discharged supersonic jet of acetonitrile and carbon disulfide. Since the transitions have been observed at frequencies corresponding to the even multiples of the rotational constant, it is concluded that the NCCS radical has a bent structure in the ground electronic state, X 2A′, and the Ka=0 ladder of the radical has been observed under the jet-cooled condition. Precise molecular constants, including the hyperfine constants of the nitrogen nucleus, are determined by a least-squares fit for the observed transition frequencies using a standard asymmetric top Hamiltonian. The determined rotational constant is compared with results of high-level ab initio calculations in order to confirm the spectral carrier to be the bent NCCS radical.

Laser-induced fluorescence spectrum of the A 3Πi←X 3Σ− transition of the CCS radical has been studied in a discharged supersonic jet of a mixture gas, carbon disulfide and acetylene diluted in Ar. More than 40 vibronic bands in the 600–925 nm region have been assigned to the transitions from the ground vibronic level of the CCS radical. The progression of the C–C stretching mode was identified for υ1=1–4, and the harmonic frequency of the mode was determined to be 1840.13(1) cm−1. In addition to the perpendicular bands, Σ–Σ parallel-type bands have been observed and assigned to vibronically forbidden transitions, A(υ1,0,1)←X(0,0,0). Based on the positions of the bands, the harmonic frequency and the Renner parameter of the bending mode in the A 3Πi state were determined to be 399.00(3) cm−1 and −0.234 67(7), respectively. High-level ab initio calculations were performed to compare the results with the experimentally determined vibronic parameters. Since the band at 778 nm has a complicated rotational st...

Laser-induced fluorescence (LIF) excitation spectra of the SiH 2 A (1,0,0) – and A (1,1,0)–X (0,0,0) bands, and dispersed fluorescence (DF) spectra from the A (1,0,0) and (1,1,0) levels were measured in the supersonic-free jet. From the rotational structures of the excitation spectra, the rotational constants in A (1, v 2 ,0), v 2 =0∼2, were determined. The fluorescence decay profiles of the single ro-vibronic levels were also measured, and the fluorescence lifetimes were determined. Based on the lifetimes, it was found that the predissociation depending on the vibronic level starts between the A (1,4,0) and (1,5,0) levels, and the predissociation depending on the rotational level in the A state is suppressed by the ν 1 mode excitation and is promoted by the ν 2 mode. The latter one is qualitatively explained by considering a second-order predissociation mechanism and a rotation-vibration constant, α i A .

New vibronic bands were observed in the 17 000–17 600 cm −1 region by laser induced fluorescence (LIF) spectroscopy in the discharged products of a mixture of C2H2 and CS2 in a supersonic jet. The effective rotational constants and the position of the vibronic band origin have been determined to be B ″ eff =0.01910(2) cm −1 , B ′ eff =0.01891(2) cm −1 , and T 0 =16961.5161(5) cm −1 , respectively. The spectral carrier of the bands has been confirmed to be the HC6S radical from the chemical behavior of the products and the determined rotational constant.

A new type of microwave-detected microwave-optical double-resonance (MODR) spectroscopy has been developed using a Fourier-transform microwave spectrometer and a tunable pulsed dye laser. In this method, a free-induction decay (FID) signal was detected instead of the microwave (MW) absorption. To demonstrate the performance, we measured the MODR spectra of the CCS and C 4 H radicals in supersonic jets generated by a pulsed-discharge nozzle. Since the pulsed sources are employed for both the optical and microwave radiations, it is possible to control the relative timing of irradiations of the MW and optical pulses. We were able to obtain two different types of spectra; one is the ordinary population labeling spectrum, and the other is a spectrum obtained by breaking the coherence of molecules. In the latter case, more than 50% of depletion of the FID signal was observed, which is unable to be attained when noncoherent phenomena are used to detect the double-resonance signal.

Vibronic band systems for the HC 4 S and DC 4 S radicals were observed in supersonic jets for the first time by laser induced fluorescence (LIF) spectroscopy. The rotational structures of the bands were resolved by high-resolution scans. It was found that all the observed bands are 2 Π 3/2 – 2 Π 3/2 transitions. Band origins and effective rotational constants of the origin bands are determined to be T 0 =19 980.687(1) and B ′ eff =0.046580(4) cm −1 for HC 4 S, T 0 =20 034.8748(9) and B eff ′ =0.044294(3) cm −1 for DC 4 S. Ab initio calculations were carried out to interpret the vibronic transitions.

Two silicon-bearing carbon chain radicals, SiC2N and SiC3N, were detected in the laboratory by Fourier transform microwave spectroscopy. Molecular constants including the hyperfine coupling constants have been determined for the two radicals in the ground electronic states. The SiC2N and SiC3N radicals have linear structures in the (2)Π ground electronic states with inverted and regular fine structures, respectively, as are the cases for their isoelectronic radicals, SiC3H and SiC4H, indicating that the SiC(n)N radicals have similar electronic structures to the SiC(n +1)H radicals. The electronic structures of SiC2N and SiC3N in the ground states are discussed on the basis of the experimentally determined molecular constants.

BACKGROUND The c-met and the c-erb B-2 protooncogenes belong to a family of tyrosine kinase growth factor receptors. Abnormalities of these oncogenes and protein products have been reported in several cancers. The authors investigated the correlation between clinical factors and amplification or overexpression of the c-met and/or c-erb B-2 gene in Japanese patients with gastric carcinoma patients, with a focus on prognostic significance. METHODS Amplification and overexpression of c-met and c-erb B-2 were investigated retrospectively in 128 gastric carcinoma patients by using immunohistochemistry and Southern blot hybridization. Survival analysis was performed with the Kaplan–Meier test, and the log rank test was used for statistical analysis. RESULTS Overexpression of c-met and c-erb B-2 was observed in 46.1% and 16.4% of gastric carcinoma cases, respectively. Gene amplification of c-met and c-erb B-2 was detected in 10.2% and 11.7% of gastric carcinoma cases, respectively. Amplification and overexpression of c-met were correlated significantly with depth of tumor invasion and lymph node metastasis, whereas amplification and overexpression of c-erb B-2 were correlated significantly with histologic type. The survival rate of patients with amplification and/or overexpression of c-met or c-erb B-2 was significantly poorer than that of patients with no amplification or overexpression. Multivariate analysis revealed that c-met overexpression and lymph node metastasis were independent prognostic factors. CONCLUSIONS These data suggest that overexpression and/or gene amplification of c-met and c-erb B-2 may be prognostic factors in gastric carcinoma. Cancer 1999;85:1894–902. © 1999 American Cancer Society.

In order to examine significant roles of conformations played in various research fields, a molecule with two internal-rotation axes of high symmetry, 1,4-pentadiene, was studied in detail through the observation of its rotational spectra by using various types of microwave spectroscopy, Stark modulation and Fourier transform in the centimeter-wave region, direct absorption in the millimeter-wave region, and centimeter-/millimeter-wave combinations for double resonance, along with ab initio molecular orbital calculations. The molecule was confirmed to exist in three rotameric forms: skew-skew, cis-skew, and skew-skew'. For the cis-skew form, rotational spectra not only in the ground vibrational state, but also in three excited C-C torsional states were detected. Rotational and centrifugal distortion constants were precisely determined by the analysis of all the observed spectra, in addition to the relative energies of the three isomers and the torsional frequencies for the cis-skew form, as estimated from the observed spectral line intensities. The skew-skew form was found to be the most stable among the three isomers, the cis-skew form higher in energy than the skew-skew by 172 ± 66 cm(-1), and the skew-skew' form higher in energy than the cis-skew by 44 ± 26 cm(-1). These experimental results were compared with those derived from a two-dimensional potential energy surface calculated by ab initio molecular orbital methods, in order to obtain a global view of molecular dynamics taking place on the surface, while paying attention to unique features of internal rotation characteristic of two dimensions.

We report herein a case of gastric sarcoidosis associated with a Non-Hodgkin's lymphoma. In June, 1991, a 40-year-old man was seen at he hospital because of upper abdominal discomfort, nausea and vomiting and was followed an ambulant basis with a diagnosis of multiple gastric ulcer. In November, 1994, histological examination of the biopsy specimen of the stomach ulcer revealed malignant lymphoma. A total gastrectomy with regional lymph nodes dissection was performed. The resected specimen of the stomach demonstrated erosion and some traces of ulcer. Histopathologically, malignant lymphoma was demonstrated in only a part of the stomach. In contract, gastric sarcoidosis was detected throughout the resected stomach and resected lymph nodes. This case appears interesting from the point of the pathogenesis of malignant lymphoma associated with sarcoidosis, since both the two lesions had been localized to the stomach. Several cases of sarcoidosis together with malignant lymphoma have been reported from the Westren countries, however, gastric sarcoidosis associated with gastric lymphoma is extremely rare, so far.

Pure rotational transitions of the dimethyl-substituted Criegee intermediate (dimethyl carbonyl oxide, acetone oxide), (CH3)2COO, were observed in the discharge plasma of a C(CH3)2I2/O2 gas mixture by Fourier-transform microwave spectroscopy. The observed spectra show small splittings due to the internal rotations of the two methyl groups. Precise rotational constants of the molecule and the barrier heights of the methyl internal rotations were experimentally determined.

This paper describes a relatively rare case of leiomyosarcoma of the esophagus recurred 9 years after the primary resection. A 59-year-old woman was admitted to the hospital because of dysphagia in April 1993. There was a previous history of undergoing operation for a leiomyosarcoma located in the upper third of the esophagus in August 1984. She had been suffering from dysphagia which started about 2 years after the first operation. Upper gastrointestinal series, esophagoscopy, MRI and angiography revealed a submucosal tumor located in upper third of the esophagus and resection of the thoracic and abdominal esophagus by blunt dissection was performed. The tumor was 3.0cm in diameter and histopathologically diagnosed as recurrent leiomyosarcoma of the esophagus of low grade malignancy. We made a comparative assessment of this tumor with primary tumor resected 9 years before, using DNA flow-cytometrical analysis, and it was revealed that the primary tumor showed aneuploidy and the recurred tumor diploidy. This paper also presents a total of 88 cases of the disease seen in the Japanese literature.

The spectra of 1-indanyl-based resonance-stabilized radicals containing a hydroxyl group are identified in an electrical discharge containing indene and its alkylated derivatives. It is argued that such species form by addition of a discharge-nascent hydroxyl radical, formed from trace water, to the π bond on the five-membered ring of the parent molecule. The spectral carriers are identified by analysis of their excitation and emission spectra guided by the results from quantum chemical calculations. All three hydroxylated radicals are found to exhibit origin bands in the 21300 cm(-1) region: the 2-hydroxy-indan-1-yl radical at 21364 cm(-1), the 2-hydroxy-2-methyl-indan-1-yl radical at 21337 cm(-1), and the 2-ethyl-2-hydroxy-indan-1-yl radical exhibiting two origins of similar intensity at 21287 and 21335 cm(-1).