The ground state of KO revisited: the millimeter and submillimeter spectrum of potassium oxide

2019 ◽  
Vol 21 (39) ◽  
pp. 21960-21965 ◽  
Author(s):  
Mark A. Burton ◽  
Benjamin T. Russ ◽  
Matthew P. Bucchino ◽  
Phillip M. Sheridan ◽  
Lucy M. Ziurys
Keyword(s):  
Excited State ◽  
Electronic State ◽  
Millimeter Wave ◽  
Ground State ◽  
Wave Spectrum ◽  
Ground Electronic State ◽  
Potassium Oxide ◽  
Direct Absorption

Measurement of the millimeter-wave spectrum of the KO radical, using direct absorption methods, suggests that the ground electronic state is X2Πi with a close-lying excited state approximately 120 cm−1 higher in energy.

scholarly journals The millimeter-wave spectrum of methyl ketene and the astronomical search for it

2018 ◽  
Vol 619 ◽  
pp. A92 ◽  
Author(s):  
C. Bermúdez ◽  
B. Tercero ◽  
R. A. Motiyenko ◽  
L. Margulès ◽  
J. Cernicharo ◽  
...  
Keyword(s):  
Excited State ◽  
Millimeter Wave ◽  
Ground State ◽  
Wave Spectrum ◽  
High Mass ◽  
Mass Star ◽  
Rotational Spectrum ◽  
Star Forming ◽  
Dark Clouds ◽  
Star Forming Regions

Context. The analysis of isomeric species of a compound observed in the interstellar medium (ISM) is a useful tool to understand the chemistry of complex organic molecules. It could, likewise, assist in the detection of new species. Aims. Our goal consists in analyzing one of the two most stable species of the C3H4O family, methyl ketene, whose actual rotational parameters are not precise enough to allow its detection in the ISM. The obtained parameters will be used to search for it in the high-mass star-forming regions Orion KL and Sagittarius B2, as well as in the cold dark clouds TMC-1 in the Taurus Molecular Cloud and Barnard 1 (B1–b). Methods. A millimeter-wave room-temperature rotational spectrum of methyl ketene was recorded from 50 to 330 GHz. The internal rotation analysis of its ground state and first torsional excited state was performed with the rho-axis method employing the RAM36 program. Results. More than 3000 transitions of the rotational spectrum of the ground state (Kamax = 18) and first torsional excited state (Kamax = 13) of methyl ketene were fitted using a Hamiltonian that contains 41 parameters with a root mean square of 44 kHz. Column density limits were calculated but no lines were detected in the ISM belonging to methyl ketene.

The Millimeter Wave Spectrum of DCNO: An Example of Current Measurements in the Frequency Range from 60 to 350 GHz

1974 ◽  
Vol 29 (4) ◽  
pp. 633-641 ◽  
Author(s):  
Manfred Winnewisser ◽  
Brenda P. Winnewisser
Keyword(s):  
Excited State ◽  
Millimeter Wave ◽  
Ground State ◽  
Preliminary Data ◽  
Wave Spectrum ◽  
Frequency Range ◽  
Simple Method ◽  
Efficient System ◽  
First Excited State ◽  
Bending Modes

An efficient system for preliminary data reduction is described which completes a recently developed data acquisition and reduction system for the measurement of millimeter wave absorption lines with the help of a dedicated computer. A simple method of automatically determining the absorption line centers is given. Rotational transitions of DCNO, measured with the above system, are reported for the ground state and the first excited state of each of the two bending modes ν4 and ν5. The rotational and rotation-vibration constants obtained for these states are B0 = 10,292.48340 (31) MHz, D0 = 3.5418 (10) kHz,Bν4 = 10,306.00780 (45) MHz, Dν4 = 3.6409 (22) kHz,Bν5 = 10,338.65942 (32) MHz, Dν5 = 3.6208 (16) kHz.The l-type doubling constants q.t0) and qt(1) agree with the values obtained previously from direct l-type doubling transitions.

Photodissociation Dynamics of the Methylsulfinyl Radical at 248 nm

2018 ◽  
Author(s):  
Isaac Ramphal ◽  
Chin Lee ◽  
Daniel Neumark
Keyword(s):  
Excited State ◽  
Electronic State ◽  
Ground State ◽  
Molecular Beam ◽  
Internal Conversion ◽  
Ground Electronic State ◽  
Electronically Excited ◽  
State Dissociation ◽  
Primary Channel

The photodissociation dynamics of jet-cooled methylsulfinyl radicals, CH3SO, at 248 nm have been investigated using molecular beam photofragment translational spectroscopy. The primary channel is CH3S + O, which occurs via the initially prepared excited CH3SO state by rapid cleavage of the S-O bond to produce ground state products. The minor SO + CH3 channel has two components in comparable proportions: a fast feature corresponding to rapid C-S cleavage on the excited state to produce CH3 and electronically excited SO, and a slow feature due to internal conversion of CH3SO followed by statistical dissociation on the ground electronic state. Statistical ground state dissociation also produces small amounts of CH2SO, likely sulfine, and H-atoms.

Photodissociation Dynamics of the Methylsulfinyl Radical at 248 nm

2018 ◽  
Author(s):  
Isaac Ramphal ◽  
Chin Lee ◽  
Daniel Neumark
Keyword(s):  
Excited State ◽  
Electronic State ◽  
Ground State ◽  
Molecular Beam ◽  
Internal Conversion ◽  
Ground Electronic State ◽  
Electronically Excited ◽  
State Dissociation ◽  
Primary Channel

The photodissociation dynamics of jet-cooled methylsulfinyl radicals, CH3SO, at 248 nm have been investigated using molecular beam photofragment translational spectroscopy. The primary channel is CH3S + O, which occurs via the initially prepared excited CH3SO state by rapid cleavage of the S-O bond to produce ground state products. The minor SO + CH3 channel has two components in comparable proportions: a fast feature corresponding to rapid C-S cleavage on the excited state to produce CH3 and electronically excited SO, and a slow feature due to internal conversion of CH3SO followed by statistical dissociation on the ground electronic state. Statistical ground state dissociation also produces small amounts of CH2SO, likely sulfine, and H-atoms.

scholarly journals Probing the excited state relaxation dynamics of pyrimidine nucleosides in chloroform solution

2016 ◽  
Vol 194 ◽  
pp. 683-708 ◽  
Author(s):  
Katharina Röttger ◽  
Hugo J. B. Marroux ◽  
Hendrik Böhnke ◽  
David T. J. Morris ◽  
Angus T. Voice ◽  
...  
Keyword(s):  
Excited State ◽  
Electronic State ◽  
Ground State ◽  
Experimental Studies ◽  
Chloroform Solution ◽  
Ground Electronic State ◽  
Triplet States ◽  
Relaxation Dynamics ◽  
State Recovery ◽  
Franck Condon

Ultrafast transient electronic and vibrational absorption spectroscopy (TEAS and TVAS) of 2′-deoxy-cytidine (dC) and 2′-deoxy-thymidine (dT) dissolved in chloroform examines their excited-state dynamics and the recovery of ground electronic state molecules following absorption of ultraviolet light. The chloroform serves as a weakly interacting solvent, allowing comparisons to be drawn with prior experimental studies of the photodynamics of these nucleosides in the gas phase and in polar solvents such as water. The pyrimidine base nucleosides have some propensity to dimerize in aprotic solvents, but the monomer photochemistry can be resolved clearly and is the focus of this study. UV absorption at a wavelength of 260 nm excites a 1ππ* ← S0 transition, but prompt crossing of a significant fraction (50% in dC, 17% in dT) of the 1ππ* population into a nearby 1nπ* state is too fast for the experiments to resolve. The remaining flux on the 1ππ* state leaves the vertical Franck–Condon region and encounters a conical intersection with the ground electronic state of ethylenic twist character. In dC, the 1ππ* state decays to the ground state with a time constant of 1.1 ± 0.1 ps. The lifetime of the 1nπ* state is much longer in the canonical forms of both molecules: recovery of the ground state population from these states occurs with time constants of 18.6 ± 1.1 ps in amino-oxo dC and ∼114 ps in dT, indicating potential energy barriers to the 1nπ*/S0 conical intersections. The small fraction of the imino-oxo tautomer of dC present in solution has a longer-lived 1nπ* state with a lifetime for ground state recovery of 193 ± 55 ps. No evidence is found for photo-induced tautomerization of amino-oxo dC to the imino-oxo form, or for population of low lying triplet states of this nucleoside. In contrast, ∼8% of the UV-excited dT molecules access the long-lived T1 (3ππ*) state through the 1nπ* state. The primary influence of the solvent appears to be the degree to which it destabilizes the states of 1nπ* character, with consequences for the lifetimes of these states as well as the triplet state yields.

Quantum dynamics of the photostability of pyrazine

2015 ◽  
Vol 17 (44) ◽  
pp. 29518-29530 ◽  
Author(s):  
Matthieu Sala ◽  
Stéphane Guérin ◽  
Fabien Gatti
Keyword(s):  
Electronic State ◽  
Ground State ◽  
Quantum Dynamics ◽  
Ground Electronic State ◽  
Conical Intersection ◽  
Radiationless Decay

We propose a new mechanism for the radiationless decay of photoexcited pyrazine to its ground electronic state involving a conical intersection between the dark Au(nπ) state and the ground state.

scholarly journals Millimeter Wave Spectrum and Centrifugal Distortion Analysis of Difluorochloromethane CHF2Cl in the Ground State

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1165-1168 ◽  
Author(s):  
R. Spiehl ◽  
A. Guarnieri
Keyword(s):  
Millimeter Wave ◽  
Ground State ◽  
Wave Spectrum ◽  
Sixth Order ◽  
Centrifugal Distortion ◽  
Rotational Spectra ◽  
Vibrational Ground State ◽  
Distortion Analysis

Abstract The rotational spectra of CHF235Cl and CHF237Cl (CFC22) in the vibrational ground state between 42 and 214 GHz are reported. A centrifugal distortion analysis up to the sixth order is carried out.

scholarly journals A deep UV trigger for ground-state ring-opening dynamics of 1,3-cyclohexadiene

2019 ◽  
Vol 5 (9) ◽  
pp. eaax6625 ◽  
Author(s):  
Jennifer M. Ruddock ◽  
Haiwang Yong ◽  
Brian Stankus ◽  
Wenpeng Du ◽  
Nathan Goff ◽  
...  
Keyword(s):  
Electronic State ◽  
Ground State ◽  
Ground Electronic State ◽  
Source Analysis ◽  
Time Resolved ◽  
X Ray Scattering ◽  
Linac Coherent Light Source ◽  
Scattering Anisotropy ◽  
Kinetics Of ◽  
Single Bonds

We explore the photo-induced kinetics of 1,3-cyclohexadiene upon excitation at 200 nm to the 3p state by ultrafast time-resolved, gas-phase x-ray scattering using the Linac Coherent Light Source. Analysis of the scattering anisotropy reveals that the excitation leads to the 3px and 3py Rydberg electronic states, which relax to the ground state with a time constant of 208 ± 11 fs. In contrast to the well-studied 266 nm excitation, at 200 nm the majority of the molecules (76 ± 3%) relax to vibrationally hot cyclohexadiene in the ground electronic state. A subsequent reaction on the ground electronic state surface leads from the hot cyclohexadiene to 1,3,5-hexatriene, with rates for the forward and backward reactions of 174 ± 13 and 355 ± 45 ps, respectively. The scattering pattern of the final hexatriene product reveals a thermal distribution of rotamers about the carbon-carbon single bonds.

scholarly journals Study of Millimeter-Wave Rotational Spectra ofTrioxane in Ground, v(A), v1(E) = 1 and v2(E) = 1 States

2009 ◽  
Vol 6 (s1) ◽  
pp. S259-S279 ◽  
Author(s):  
Masoud Motamedi ◽  
Najmehalsadat Khademi
Keyword(s):  
Excited State ◽  
Excited States ◽  
Millimeter Wave ◽  
Ground State ◽  
Vibrational States ◽  
Rotational Spectra ◽  
First Time

The millimeter-wave rotational spectra of the ground and excited vibrational states v(A), v1(E) =1 and v2(E ) =1 of the oblate symmetric top molecule, (CH2O)3, have been analyzed again. The B0= 5273.25747MHz, DJ= 1.334547 kHz, DJk= -2.0206 kHz, HJ(-1.01 mHz), HJK(-3.80 mHz), and HKJ(4.1 mHz) have been determined for ground state. For non degenerate excited state, vA(1), the B = 5260.227723 MHz and DJand DJKwere determined 1.27171 kHz and -1.8789 kHz respectively. The 1=±1 series have been assigned in two different excited states v1(E) =1 and v2(E) =1.Most of the parameters were determined with higher accuracy compare with before. For the v2(E) =1 state the Cζ=-1940.54(11) MHz and qJ= 0.0753 (97) kHz were determined for the first time.

Millimeter-wave spectrum of 74GeH3F: Ground state

1983 ◽  
Vol 98 (2) ◽  
pp. 502-504 ◽  
Author(s):  
Stephen Cradock ◽  
John G. Smith
Keyword(s):  
Millimeter Wave ◽  
Ground State ◽  
Wave Spectrum
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