The 7500 to 4500 Å absorption system of the free HCO radical

1955 ◽  
Vol 233 (1192) ◽  
pp. 34-54 ◽  
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Flash Photolysis ◽  
Lower State ◽  
Absorption System ◽  
Molecular Plane ◽  
Bending Mode ◽  
Vibrational Levels ◽  
Other Substances ◽  
Low Dispersion

A fairly extensive absorption spectrum o f the free HCO radical produced by flash photolysis of acetaldehyde and other substances has been investigated with long absorbing paths and under high resolution. The corresponding DCO spectrum has also been studied. The absorption spectrum consists of simple bands with P, Q and R branches. It is shown that the molecule is linear in the upper state, but bent in the lower state with an angle of about 120° and a CO bond length of approximately 1.20 Å. Rotational constants of HCO and DCO in both upper and lower states have been derived. Various arguments based on the high-resolution measurements lead to the conclusion that the main progression of bands corresponds to transitions to the vibrational levels of the upper state with even v' 2 (the vibrational quantum number of the bending mode). This conclusion is confirmed by the observation under low dispersion of some of the intermediate bands with odd v’ 2 which are diffuse and therefore not easily recognizable under high resolution. Apparently all levels of the upper state with l≠0 are predissociated. The type of the electronic transition is shown to be 2 Σ+ ← 2 A”, that is, the transition moment is perpendicular to the molecular plane. The lower state cannot arise from normal CO and H.

High resolution absorption spectrum of nitric oxide (NO) in the region of the first ionization limit

1976 ◽  
Vol 54 (20) ◽  
pp. 2074-2092 ◽  
Author(s):  
E. Miescher
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Ionization Energy ◽  
Dissociation Limit ◽  
Matrix Elements ◽  
Rydberg Series ◽  
Isotopic Species ◽  
Vibrational Levels ◽  
Energy Formula ◽  
Ionization Limit

The absorption spectrum of cold NO gas has been photographed at high resolution between 1400 and 1250 Å for two isotopic species. Resolved bands of the Rydberg series converging to vibrational levels of the 1Σ+ ground state of NO+ are studied. They include nf–X bands up to n = 15 and ns–X bands up to n = 11, all of which show sharp rotational structure. The higher members of the np–X series are generally very diffuse with only npσ being sufficiently sharp to show broadened rotational lines. Also mostly diffuse are the ndδ–X bands. The bands ndσ, π–X are not observed. The rapidly (n−3) narrowing structure of the nf complexes is discussed and the ionization energy [Formula: see text] accurately determined by extrapolation of selected rotational lines. Interactions between Rydberg states are numerous, s ~ d mixing produces a strong effect above n = 6 when (n + 1)s levels fuse with nl levels into 'supercomplexes'. Matrix elements are given for observed 8f ~ 9s and 6f ~ 6dδ interactions.Valence levels are not observed above the ionization energy, except for the repulsive state A′2Σ+ arising from the first dissociation limit and seemingly assuming Rydberg character at molecular internuclear distance. Observed anomalies are qualitatively discussed.

The absorption spectrum of C2H2 around ν1 + ν3: energy standards in the 1.5 μm region and vibrational clustering

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1241-1250 ◽  
Author(s):  
Q. Kou ◽  
G. Guelachvili ◽  
M. Abbouti Temsamani ◽  
M. Herman
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
High Resolution ◽  
Rotational Analysis ◽  
Vibrational Assignment ◽  
Calibration Standards ◽  
Vibrational Levels ◽  
Vibrational Transitions ◽  
The Fourier Transform ◽  
Anharmonic Couplings

We have recorded the Fourier transform absorption spectrum of acetylene, C2H2, at high resolution, around 6500 cm−1. The positions of the strongest rovibrational lines are measured with respect to the rovibrational lines in 3-0 of CO. They provide secondary calibration standards in that range with an accuracy of 3 × 10−4 cm−1. The rotational analysis of the data gives evidence of five vibrational levels of [Formula: see text] symmetry, in addition to the bright combination level (1010000). This is demonstrated to strictly fit the predicted anharmonic resonance pattern in that region, which permits the vibrational assignment of those extra transitions. Study of the relative intensities of the reported vibrational transitions suggests the need to include new quartic anharmonic couplings. This is supported by the rovibrational analysis of the cold bands around 8500 cm−1, involving the (1110000) bright level, which is also presented.

The carbon monoxide flame bands

1963 ◽  
Vol 275 (1362) ◽  
pp. 431-446 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Excited State ◽  
High Resolution ◽  
Energy Level ◽  
Vibrational Level ◽  
Ground State ◽  
Fermi Resonance ◽  
Absorption System ◽  
Weak Absorption ◽  
Vibrational Levels

The carbon monoxide flame bands have been photographed under high resolution from an afterglow source. Bands in the wavelength range 3100 to 3800 Å show a pattern which has been reproduced by calculations of the energies of high vibrational levels of the ground state of CO 2 . The structure of this energy level pattern is strongly affected by extensive Fermi resonance in the 1 Σ + g state. The spectrum is emitted by excited CO 2 molecules which radiate to the ground state from the lowest vibrational level and from the v ´ 2 = 1 level of a B 2 state. This excited state lies approximately 46 000 cm -1 above the lowest level of the ground state, an d has an OCO angle of 122 + 2° and a CO bond length of 1*246 ± 0*008 Å. Combination of these results with the work of other authors shows that the excited state is a 1 B 2 state, and that the carbon monoxide flame bands are associated with the weak absorption system of CO 2 at 1475 Å.

The absorption spectrum of NH2 between 6250 and 9500 Å

1976 ◽  
Vol 54 (17) ◽  
pp. 1804-1814 ◽  
Author(s):  
J. W. C. Johns ◽  
D. A. Ramsay ◽  
S. C. Ross
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Ground State ◽  
Absorption System ◽  
Molecular Constants ◽  
Bending Vibration ◽  
Long Wavelength ◽  
Vibrational Levels

The earlier analysis by Dressier and Ramsay of the [Formula: see text] absorption system of NH2 has been considerably extended at the long wavelength end of the spectrum. All the low-lying vibronic levels of the excited state have been identified up to ν2′ = 8. These levels are 010(K = 0), 020(K = 1), 030(K = 0,2), 040(K = 1,3), 050(K = 0,2,4), 060(K = 1,3,5), 070(K = 0,2,4,6), and 080(K = 1,3,5,7). Large perturbations (~ 200 cm−1) have been observed between some of these levels and high vibrational levels of the ground state. Accurate molecular constants have been obtained for the ground state and for the first level involving the bending vibration (ν2″ = 1).

THE ABSORPTION SPECTRUM OF THE Si2 MOLECULE

1963 ◽  
Vol 41 (1) ◽  
pp. 152-160 ◽  
Author(s):  
R. D. Verma ◽  
P. A. Warsop
Keyword(s):  
Absorption Spectrum ◽  
Dissociation Energy ◽  
Ground State ◽  
Flash Photolysis ◽  
Lower State ◽  
The Third ◽  
Photolysis Apparatus ◽  
Vibrational Constants

Three band systems of Si2 have been found in absorption with a flash photolysis apparatus. Two of the band systems at 3200 and 2100 Å are new, whereas the third is an extension of the 3Σ–3Σ system observed by Douglas in emission. All three systems have the same lower state and arise from [Formula: see text] transitions. It is very probable that the [Formula: see text] state is the ground state of the Si0 molecule. Rotational and vibrational constants of all four 3Σ states have been determined. The dissociation energy of Si2 is estimated to be 3.0 ± 0.2 ev.

High resolution absorption studies of the b1Πu ← X1Σg+ system of nitrogen

1969 ◽  
Vol 47 (5) ◽  
pp. 563-589 ◽  
Author(s):  
P. K. Carroll ◽  
C. P. Collins
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Triplet State ◽  
Rotational Structure ◽  
Dissociation Limit ◽  
Rydberg Series ◽  
Absorption Studies ◽  
Vibrational Levels ◽  
Single Transition ◽  
Made In

New high resolution studies of the absorption spectrum of N2 have been made in the region 1015–795 Å. Analyses are given of 25 non-Rydberg bands of the type 1Πu–X1Σg+. It is shown that all of these bands, which include the i, j, b, l, m, p, and q groups of Worley, together with several new bands not previously observed, can be assigned to a single transition the upper state of which is called b1Πu. The pronounced irregularities in the vibrational and rotational structure of the b state are attributed to a homogeneous interaction with the first member (n = 3) of the ---(3σg) npπu, 1Πu Rydberg series. This perturbation is discussed in the accompanying paper by Dressier who recognized its importance in the interpretation of the spectrum. Diffuseness in the rotational lines of several bands at lower ν was observed and is attributed to predissociation by a triplet state, probably the C′ 3Πu state which goes to the 4S + 2D dissociation limit. Three levels of the b state show measurable Λ-type doubling which can be interpreted as caused by interaction with vibrational levels of the first member (n = 4) of the --(3σg) npσu, 1Σu+ Rydberg series. The assignment of 28 non-Rydberg 1Σu+ levels, including the b′, g, f, r, s, and t "states", to a single 1Σu+ state which is called b′, is also briefly discussed.

New results on the D2Π and B′2Π states of the PO molecule

1976 ◽  
Vol 54 (6) ◽  
pp. 695-708 ◽  
Author(s):  
S. Ghosh ◽  
S. Nagaraj ◽  
R. D. Verma
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Vibrational Level ◽  
Rotational Analysis ◽  
X Band ◽  
Vibrational Levels ◽  
Π State

A rotational analysis of the D–X and D′–X band systems of PO in the region 1900–2100 Å has been reinvestigated from an absorption spectrum taken at high resolution. A new ν = 1 vibrational level of the D2Π state of PO interacting with a new vibrational level of the D′2Π state has been studied in detail. Two other new vibrational levels, ν = 2 and 3, of D2Π have been recorded and studied in detail. A rigorous deperturbation of the D and D′ levels has been carried out. It has been shown that D′2Π and B′2Π are one and the same state of the PO molecule. A new band overlapped by the D′–X, 26–0 band has been attributed to the B2Σ+–X2Π transition.

Spectrum of SO: Analysis of the B3Σ−–X3Σ− and A3 Π–X3Σ− band systems

1969 ◽  
Vol 47 (9) ◽  
pp. 979-994 ◽  
Author(s):  
R. Colin
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Microwave Discharge ◽  
Flash Photolysis ◽  
Band System ◽  
Rotational Analysis ◽  
Rotational Constants ◽  
Π State

The absorption spectrum of SO radicals produced by flash photolysis of a mixture of COS + O2 + Ar is investigated. A partial rotational analysis of the previously known bands of the B3Σ−–X3Σ− transition which lie in the region of 1900 to 2400 Å is presented, and the predissociations and perturbations of the B3Σ−state are discussed. A complex red-degraded band system near 2500 Å, previously observed in emission and attributed to SO2, is shown to be due to a 3Π–X3Σ− transition of the SO molecule. Effective rotational constants of the 3Π state are derived from the analysis of these bands photographed at high resolution. In order to obtain the vibrational numbering of the 3Π–X3Σ− bands, these were also photographed in emission from a microwave discharge through a mixture of S18O2 + S16O2. A general discussion of the currently known states of the SO molecule is given.

The Absorption Spectrum of D2 from 1100 to 840 Å

1974 ◽  
Vol 52 (12) ◽  
pp. 1110-1136 ◽  
Author(s):  
I. Dabrowski ◽  
G. Herzberg
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Detailed Comparison ◽  
Electronic Energy ◽  
Dissociation Limit ◽  
Convergence Error ◽  
Vibrational Levels ◽  
Vibrational Constants

The absorption spectrum of D2 has been studied in absorption at high resolution (0.254 Å/mm) in the region 1100 to 840 Å. The three band systems B1Σu+ ← X1Σg+ (Lyman bands), B′ 1Σu+ ← X1Σg+ and C1Πu ← X1Σg (Werner bands) have been measured right up to the dissociation limit. New improved values of the rotational and vibrational constants in the three upper states have been derived. By comparing the electronic energy differences Tc thus obtained with the corresponding values for H2 fairly precise values for the electronic isotope shifts for the B–X and C–X systems have been determined (+ 2.8 and −7.4 cm−1 respectively). In this connection two gaps in the knowledge of the absorption spectrum of H2 have been filled: the Lyman bands with ν′ = 5–16 and the Werner bands with ν′ = 0–4 (see Appendix). A detailed comparison is made of the observed vibrational levels and the observed Bν values of D2 with those derived from ab initio calculations based on the Kotos and Wolniewicz' potential functions. From the observed electronic isotope shift the adiabatic corrections can be estimated near the minimum. For the B state these estimates agree very well with the ab initio calculations. The remaining differences between observation and theory are partly due to lack of convergence of the Born–Oppenheimer calculation, partly to the neglect of nonadiabatic corrections. The convergence error near minimum is estimated to be 5.1 cm−1 for the B state and 1.2 cm−1 for the C state.

The Electronic Spectrum of HF. I. The B1Σ+–X1Σ+ Band System

1973 ◽  
Vol 51 (4) ◽  
pp. 434-445 ◽  
Author(s):  
G. Di Lonardo ◽  
A. E. Douglas
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Emission Spectrum ◽  
Electronic Spectrum ◽  
Dissociation Energy ◽  
Band System ◽  
Vibrational Levels ◽  
Internuclear Distances ◽  
X State ◽  
Potential Curves

The electronic emission and absorption spectrum of HF has been photographed at high resolution with a 10 m grating spectrograph. The emission, which extends from 2670 to 1480 Å, consists entirely of bands of the B1Σ+–X1Σ+ (previously denoted as the V1Σ+–X1Σ+)system. From the analysis of 51 bands of the emission spectrum, constants of the vibrational levels of the X state from ν = 7 and 19 and of the B state from ν = 0 to 10 have been determined. The dissociation energy of HF has been found to be D0(HF) = 47 333 ± 60 cm−1. In the absorption spectrum, 56 bands of the B–X system have been identified. Vibrational levels of the B state between ν = 14 and 26 were found to be well behaved and readily analyzed, but levels between ν = 26 and 73 were found to be highly perturbed. Rydberg–Klein–Rees potential curves have been calculated for the B and X states and it is shown that at large internuclear distances the bonding of the B state is almost entirely ionic.

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