Red Band System Research Articles

Intracavity laser absorption spectroscopy measurements of CN using red system A–X. Simultaneous observation of CN, NH 2, HNO and [formula omitted] in low pressure hydrocarbon flames doped with nitrogen oxides

Absorption spectra of the CN radical have been measured by Intracavity Laser Absorption Spectroscopy in hydrocarbon flames doped with minor amount of nitrogen oxide. Spectra of the CN red band system ( A 2Π← X 2Σ + ) have been observed in the spectral range of 642 nm along with lines of other species from flame: NH 2, HNO, 1 CH 2 , and NO 2. The sensitivity of about 2.3×10 10 cm −3 at 1700 or ∼100 ppb at 30 Torr at 1700 K has been demonstrated.

New Assignments in the Green and Red Band Systems of the FeH Radical

The electronic spectrum of FeH in the regions of the 532 nm (green) and 630 nm (red) systems has been investigated using the techniques of dispersed and undispersed laser induced fluorescence. Sixteen lines have been assigned in the Ω = 1/2 ← Ω = −1/2 subband of the e6Π–c6Σ+transition and term values determined for the previously uncharacterized e6Π1/2spin–orbit component. A further fourteen lines were assigned to the connected Ω = 1/2 ← Ω = 3/2 subband of the e6Π–a6Δ transition and term values for the hitherto uncharacterized a6Δ3/2component were determined. A study of the high-temperature spectrum of FeH, recorded previously by McCormack and O'Connor (1), enabled the branches of the Ω = 7/2 ← Ω = 9/2 subband of the e6Π–a6Δ transition to be extended to higher J values. These predictions were confirmed by laser induced fluorescence (LIF) experiments and led to the assignment of 13 additional lines in this subband. The term values for the e6Π7/2and a6Δ9/2spin–orbit components were thus extended to higher J values.

Theoretical analysis of the emission spectra of the NaCd excimer

We present simulations of bound–bound and bound–free emissions of the NaCd* excimer, along with new experimental results concerning the red band system. The simulations, based on ab initio potential energy curves, confirm that the initial states are 2 2Σ+ for the red emission and 2 2Π for the blue emission of NaCd*. The two main peaks in the blue band system are due to spin–orbit splitting. The band shape obtained in the simulations is extremely variable, depending on the population distribution of the vibrational states of NaCd*. The comparison of simulated and measured spectra leads us to conclude that, in the experimental conditions adopted here and in previous work, the thermal equilibration of the excimer is far from complete.

Rotational Analysis of two Red Band Systems in the ThO Spectrum

Two band systems in the red region of ThO spectrum have been analysed. The systems are called R – H and S – Q. The H and Q states are known low lying excited states. The new found excited states R and S have Ω = 0- and 3 respectively. Small pertubations in the R state are studied. The upper and lower states of the previously analysed "5579 Å" band have been indentified and put into the term scheme.

Laser spectroscopic investigations of the red band systems of CaH

Gaseous CaH has been the subject for laser spectroscopic investigations with special emphasis on perturbations appearing in the A 2Π- X 2Σ and B 2Σ- X 2Σ transitions, and on extension of the earlier analysis to v = 3. Penetrations to an outer potential minimum B′ of the B state have been observed. From the positions of the tunneling levels the energy T 0 ≈ 19525 cm −1 and the rotational constant B 0 ≈ 2.2 cm −1 are estimated for the lowest level of the B′ state. Eighteen previously unassigned branches belonging to the A- X (1, 0), (2, 1), (3, 2), (1, 1), (2, 2), and (3, 3), and B- X (3, 3) transitions are presented together with a revised analysis of the A 2 Π 3 2 v = 1 and v = 2 levels. A new calculation of the ground state molecular constants (cm −1) has been performed, and a deperturbation of the A 2Π, B 2Σ, B′ 2Σ energy system is presented. The molecular constants obtained for the ground state are (numbers in parentheses refer to one standard deviation in the last digits) Te -644.306 γD -3.43(71)10 −6 ωe 1298.057(23) Be 4.27649(11) ωeXe 18.863(14) α 0.096175(33) ωeYe -0.0561(25) δe -0.000353(11) γe 0.0436(6) De 1.8367(14)·10 −4 α γ -0.0014(2) He 5.445(47)·10 −9

Raman studies in CuTCNQ: Resonance Raman spectral observations and calculations for TCNQ ion radicals

The Raman spectra of thin film, and powdered crystalline forms of CuTCNQ have been studied and analyzed in connection with their electronic spectra and vibrational normal coordinate analysis and molecular orbital results. Nonresonance and resonance Raman conditions have been obtained by using different sample forms and source wavelengths. Shifts of TCNQ− and TCNQ= vibrational frequencies from those of TCNQ0 due to changes in the charge on the TCNQ moiety have been calculated in terms of molecular orbital parameters and TCNQ0 vibrational frequencies. The resonance Raman enhancement of TCNQ− in the red band system is shown to be of Franck–Condon origin and its resonance Raman spectrum in this region is calculated. Transformation of CuTCNQ to TCNQ0 with different laser lines is explained on the basis of photoinduced electronic transitions.

Chemiluminescent spectra of YbF and YbCl

We have obtained the chemiluminescent spectra of YbF and YbCl from the reactions of ytterbium with fluorine and ytterbium with chlorine dioxide under beam-gas conditions and in a high-pressure (3 Torr) flow system. Much more extensive band systems are observed than hitherto reported, and a vibrational reanalysis of the ground and low-lying states is made. Although the A- X and B- X systems appear regular in YbCl, the A 2 Π 1 2 -X 2 Σ + and B- X systems in YbF exhibit extensive vibrational perturbations. The interaction between molecular states arising from the separated atoms Yb(5 d) + X( np) as well as Yb(6 p) + X( np) is believed to cause these perturbations. An unassigned red-band system is observed in emission for both YbF and YbCl, suggesting that the lowest-lying excited state is not the A state.

Study of the electronic transition moment for the CN red band system

The Rydberg-Klein-Rees (RKR) potential energy curves of the X 2Σ + state and the A 2∏ i state of CN have been calculated by using the recent data of Poletto and Rigutti. (6) The RKR Franck-Condon factors and r-centroids for the CN red band system have been computed. These have been used, in conjunction with the relative band oscillator strengths reported by Lambert, (3) to determine the variation of the electronic transition moment, R e ( r), with the internuclear separation, r. The expression for R e ( r) obtained has been found to be in good agreement with that obtained by using the data of Dixon and Nicholls (1) on the relative emission intensity distribution in the red band system of CN.

The Spectrum of CuO: Rotational Analysis of Some Blue and Red Bands

The emission spectrum of CuO has been photographed at high resolution in the region from 4 000 Å to 6 500 Å. In the red region also the pure isotopic molecule 63CuO has been studied. Different light sources have been used. A blue band system, a 2Πi-X2Πi transition, as well as a red band system, a 2Σ+-X2Πi transition, has been rotationally analyzed. Tables of the molecular constants of all the known states of CuO are given.

A shock tube determination of the electronic transition moment of the CN red band system

The electronic transition moment of the CN red band system and its variation with internuclear separation have been determined absolutely from spectral emission measurements behind incident shock waves. The unshocked test gas was a 23.6% CO-76.4% N 2 mixture, and the temperature behind the incident shock was typically 6158°K. The value obtained for the electronic transition moment Σ|R eea 0| 2 was 0.32±0.06, corresponding to an electronic absorption ƒ-number ƒ el(λ) of (4.5 ± 0.9) × 10 -3 at a wavelength of 10,970 Å. These data are based on a CN ground state (X 2Σ +) dissociation energy of 7.89 eV previously measured by the present authors during a similar study on the CN violet system. The variation of the electronic transition moment with inter-nuclear separation was found to be small.

Confirmation of the red band system in MnO4-as1T1←1A1from the effect of pressure on single crystal absorption spectra

The application of uniaxial pressure to single crystals of LiClO4 . 3H2O/LiMnO4. 3H2O and Ba(ClO4)2. 3H2O/Ba(MnO4)2. 3H2O has led to a large splitting of the zerophonon origin line at 13 772 cm-1 in the absorption spectrum of the lithium salt and a much smaller splitting of the 14 247 cm-1 line in the corresponding spectrum of the barium salt. Furthermore, a third line at ∼ 13 764 cm-1 appears in the spectrum of the lithium salt at high pressures. The polarization behaviour of the three lines from the lithium salt is exactly as would be expected for a forbidden electric-dipole 1 T 1 ← 1 A 1 transition in the parent tetrahedral point group.

Vibrational Levels in the Red CuO-Bands

ROSEN1 has recently reported an investigation on the band-spectrum of CuO and given formulae for the representation of the band-heads, as the result of a vibrational analysis. I have performed a rotational and vibrational analysis of five bands in the red part of the CuO-spectrum2, and I have computed the following formula for the band-origins: The constants in this formula differ from the constants in Rosen's formula, particularly in the ground-state, where Rosen's values are about twice as great as my values. I had intended to wait until my investigation on the blue and green bands of CuO, which continues my work on the red band-system, had been completed before drawing further conclusions from the vibrational analysis ; but Rosen's report makes a comparison between his and my formula for the red band-system desirable.

Rotational Structure of the Red Bands of Sodium

Three bands of the red band system of sodium photographed at high dispersion have been measured. Two strong series of lines run through the bands and from the combination relations it is quite certain that these series are bona fide $P$ and $R$ branches. From the combination relations we find ${{B}_{0}}^{\ensuremath{'}\ensuremath{'}}=0.15435$, ${{D}_{0}}^{\ensuremath{'}\ensuremath{'}}=\ensuremath{-}5.89\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ and ${{B}_{0}}^{\ensuremath{'}}=0.10846$. The final state values are in close agreement with those of the final state of the blue green system and the constant for the upper state yields ${{I}_{0}}^{\ensuremath{'}}=255.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}40}$ gm ${\mathrm{cm}}^{2}$ and ${{r}_{0}}^{\ensuremath{'}}=3.52\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ cm. Search is made for other branches but none are found. From a discussion of the possible electronic transitions it is concluded that the electronic transition is the $^{1}S\ensuremath{-}^{1}S$ type.

New Features of the Red Band System of Sodium

New Features of the Red Band System of Sodium