The simplest Criegee intermediate CH2OO was detected in a discharged supersonic jet of CH2Br2 and O2 gas mixture by Fourier-transform microwave spectroscopy. experimentally determined rotational constants its isotopologues enabled us to derive the geometrical structure. OO CO bond lengths, which are relevant discussion on electronic structure, 1.345(3) 1.272(3) Å, respectively. length is close that typical double shorter than 0.07 indicating has more zwitterionic character H2C = O(⊕)-O(⊖)...

We found four series of harmonically related lines in IRC +10216 with the Yebes 40 m and IRAM 30 telescopes. The first corresponds to a molecule rotational constant, B , 1448.5994±0.0013 MHz distortion D 63.45±1.15 Hz covers upper quantum numbers from J u = 11 up 33 (B1449). second is fitted 1446.9380±0.0098 91±23 17 (B1447). third 598.7495±0.0011 6.13±0.43 26 41 (B599). Finally, frequencies last can be reproduced 594.3176±0.0026 4.92±1.16 (B594). large values point toward metal-bearing...

The pure rotational spectrum of the methoxy radical in 2E ground electronic state was observed mm-wave region using a source-frequency modulation microwave spectrometer with 1 m long free space absorption cell. produced cell by reaction methanol 2450 MHz discharge products CF4. Each transition found to split into fine and hyperfine components. A Hamiltonian derived which includes spin-orbit interaction, vibronic Coriolis (2,−1) (2,2) rovibronic interactions, interaction. It successfully...

The microwave spectra of the HSO and DSO radicals in ground state were observed glow discharges a mixture H2S or D2S O2. Both a-type b-type transitions assigned analyzed. hyperfine coupling constants hydrogen nucleus determined for first time. These resulted conclusion that electronic is 2A″. rotational constants, centrifugal distortion spin–rotation including their terms both species also with good precision. diagonal components magnetic interaction deuterium not obtained because most...

The ν3 fundamental band of the CH3 radical has been detected in absorption with a tunable difference frequency laser. Zeeman modulation is found to be inefficient, because spin-rotation interaction small. molecular constants vibrational state have determined ground fixed at values from analysis ν2 band. main parameters thus obtained are origin ν0=3160.8212(12), B3=9.471 10(14), C3=4.701 67(15), (Cζ)3=0.345 88 (22), and q3=0.006 42(25), all cm−1 one standard deviation parentheses. transition...

An alkyl-substituted Criegee intermediate syn-CH3CHOO was detected in the gas phase through Fourier-transform microwave spectroscopy. Observed pure rotational transitions show a small splitting corresponding to A∕E components due threefold methyl internal rotation. The constants and barrier height of hindered rotation were determined be A = 17 586.5295(15) MHz, B 7133.4799(41) C 5229.1704(40) V3 837.1(17) cm(-1). High-level ab initio calculations which reproduce experimentally values well...

We report on the detection of two series harmonically related doublets in IRC +10216. From observed frequencies, rotational constant first is B = 1380.888 MHz and that second 1381.512 MHz. The correspond to species with a 2 Σ electronic ground state. After considering all possible candidates, based quantum chemical calculations, assigned MgC 3 N 4 H. For latter species, optical spectroscopy measurements support its identification. Unlike diatomic metal-containing molecules, line profiles new...

We report the detection in TMC-1 of protonated form C3S. The discovery cation HC3S+ was carried through observation four harmonically related lines Q band using Yebes 40m radiotelescope, and is supported by accurate ab initio calculations laboratory measurements its rotational spectrum. derive a column density N(HC3S+) = (2.0 +/- 0.5)e11 cm-2, which translates to an abundance ratio C3S/HC3S+ 65 20. This comparable CS/HCS+ (35 8) factor about ten larger than C3O/HC3O+ previously found same...

Using the Yebes 40m and IRAM 30m radiotelescopes, we detected two series of harmonically related lines in space that can be fitted to a symmetric rotor. The have been seen towards cold dense cores TMC-1, L483, L1527, L1544. High level theory

We report the discovery of C 5 H + cation toward TMC-1 with QUIJOTE line survey. Four lines from J = 7 − 6 up to 10 9 have been identified in perfect harmonic frequency relation that can be fit B 2411.94397 ± 0.00055 MHz and D 138 3 Hz. The standard deviation is 4.4 kHz. After discarding potential candidates, among them, we conclude carrier , for which accurate ab initio calculations provide 2410.3 MHz. also first time a cold starless core detection cation. column densities derive are (8.8...

We report the discovery in TMC-1 of two cyano derivatives PAH acenaphthylene (C 12 H 8 ). have found series lines with QUIJOTE line survey that we assign to 1-C 7 CN and 5-C CN. For 1-isomer, detected assigned 173 rotational transitions J up 46 K a 9, corresponding 107 independent frequencies. 5-isomer, identification is based on 56 individual lines, 117 40 8. Identification carriers was achieved through careful analysis derived constants, which permit us focus molecules larger than...

Pure rotational spectra of a few Van der Waals complexes containing short-lived species have been observed in our laboratory. They are produced supersonic jet by using pulsed-discharge-nozzle (PDN) system combined with Balle–Flygare Fabry–Perot type Fourier-transform microwave (FTMW) spectrometer. Among the so far observed, detailed analysis Ar—OH is presented this paper. This complex has unquenched orbital and electron-spin angular momenta, which couple large amplitude motion complex. Fine...

The adduct of the hydroxyl radical with oxygen has been studied theoretically, in connection atmospheric reactions, but its stability and structure remained an open question. Pure rotational spectra HOOO DOOO radicals have now observed a supersonic jet by using Fourier-transform microwave spectrometer pulsed discharge nozzle. molecular constants extracted from 12 transitions fine hyperfine splittings support trans planar structure, contrast to cis predicted most ab initio calculations. bond...

The pure rotational spectra of the HCCO and DCCO radicals were observed for first time in submillimeter-wave region. radical was generated by either C2H2+O reaction or H2CCO+F reaction. former found to be about twice as efficient latter, employed obtaining using C2D2 a precursor. fitted pattern near prolate symmetric top with large A constant. spin-rotation splittings result an extremely εaa constant exhibit anomalous K dependence, indicating that there is low-lying excited electronic state...

The ν1 (O–H stretching) band of the HO2 radical was observed in absorption by using a difference frequency output obtained from an Ar ion laser and cw dye as source, combined with multiple-reflection discharge cell. Zeeman modulation employed to improve sensitivity. generated directly cell dc mixture allyl alcohol oxygen. About 280 lines were analyzed precisely determine rotational constants, centrifugal distortion spin-rotation interaction constants ν1=1 state. origin determined be...

Peroxy radicals and their derivatives are elusive but important intermediates in a wide range of oxidation processes. We observed pure rotational transitions the water-hydroperoxy radical complex, H2O-HO2, supersonic jet by means Fourier transform microwave spectrometer combined with double-resonance technique. The were found to split into two components because internal rotation water moiety. molecular constants for determined precisely, supporting structure which HO2 acts as proton donor...

Rotational spectra of CH3CHD2 were observed by using a source-modulation microwave spectrometer. Of 26 transitions, 16 showed splittings due to internal rotation. An analysis the spectra, which utilized an axis method modified include centrifugal distortion effects, gave following results: A=60 809.592 (59) MHz, B=17 770.87 (16) C=17 084.84 F=257.70 (35) GHz, and V3=2.8783 (28) kcal/mole, with 2.5 times standard errors in parentheses. In V6=0 was assumed, D, constant associated cross product...

Our observations of TMC-1 with the Yebes 40 m radio telescope in 31.0–50.3 GHz range allowed us to detect a group unidentified lines, showing complex line pattern indicative an open-shell species. The observed frequencies these lines and similarity spectral that 2 0, –1 1 rotational transition H CCN indicate arise from deuterated cyanomethyl radical, HDCCN. Using Fourier transform microwave spectroscopy experiments combined electric discharges, we succeeded producing radical HDCCN laboratory...

We report on the detection of a series six lines in ultra-deep Q-band integration toward IRC+10216 carried out with Yebes 40m telescope, which are harmonic relation integer quantum numbers J from 12 to 18. After detailed analysis all possible carriers, guided by high-level chemical calculations, we conclude that belong HMgCCCN, named hydromagnesium cyanoacetylide. The rotational temperature and column density derived for HMgCCCN 17.1 +/- 2.8K (3.0 0.6) e12 cm-2, respectively. observed...

We present the discovery with QUIJOTE line survey of cations HC 5 N + and 7 in direction TMC-1. Seven lines half-integer quantum numbers from J = 25/2–23/2 to 37/2–35/2 have been assigned eight 55/2–53/2 71/2–69/2 . Both species inverted 2 Π ground electronic states very good estimates for their B 0 A SO constants based on optical observations. The lowest exhibit multiple components due hyperfine structure introduced by H nuclei. However, these different collapse higher No is found any...

Rotational spectra of CnO with n=2, 4, 6, and 8 have been observed by using a Fabry–Perot type Fourier-transform microwave spectrometer cooperated pulsed discharge nozzle. The molecules generated an electric carbon suboxide diluted in Ar, adiabatically cooled to ≊2 K subsequent supersonic expansion. All the for these species are characterized as linear 3Σ− electronic ground state. Since all three spin sublevels detected even free-jet condition, spin–spin coupling constants determined...