Variation Of Electronic Transition Moment Research Articles

Theoretical study of the radiative properties of the A1Π- X1Σ+ system of the GeO molecule

Absolute oscillator strengths and related radiative properties of the A 1 Π- X 1 Σ + transition of the GeO molecule have been determined from accurate ab initio MRCI calculations. The reported results include the electronic transition moment variation, absolute transition probabilities, absolute and relative vibronic oscillator strengths and radiative lifetimes of the lowest vibrational levels of the excited electronic state. The few experimental data are critically discussed in the light of the present work. Comparison of GeO with CO and SiO show the close similarity of the transition mechanism in the three molecules.

Study of the B(O+u)→X(1Σ+g) system of Au2 and of the A(1Σ+u)→X(1σ+g) system of Ag2

Abstract In the present work the emission spectra of the B(O + u )→X( 1 Σ + g ) system of Au 2 and the A( 1 Σ + u )→X( 1 σ + g ) system of Ag 2 have been studied and the relative intensities of 28 bands of the first and 33 of the second are given. Internuclear potential, Franck—Condon factors and r -centroids have been calculated in order to study the variation of electronic transition moment vs r -centroid. Also, some features of rotovibrational populations of excited levels of these species in hollow-cathode discharge have been inferred.

Variation of electronic transition moment for the band system (B1 →X 1 Σ +) of PbO

The Franck-Condon factors andr-centroids have been computed by the more reliable numerical integration procedure for the bands of the (B1 →X 1 Σ +) system of the PbO molecule, using the suitable potential. The electronic transition moment variation with internuclear distance has been re-evaluated and this is represented by $$R_e \left( r \right) = const.\left( {0.525r - 1} \right)$$ in the range of 2.022×10−10 m≤r≤2.144×10−10 m. It is interesting that this representation is found to be similar to the form ofR e(r) for the band systems (AO + →X 1 Σ +) and (D1 →X 1 Σ + of PbO. Also the relative band strengths are derived. The form ofR e(r) reported by Dube et al is found to be in error.

Reinvestigations on the electronic transition moment variation in (A 2 Π -X 2 Σ +) and (B 2 Σ + -X 2 Σ +) band systems of BO molecule

The variation of electronic transition moment with internuclear distance in the case of (A 2 Π -X 2 Σ +) and and (B 2 Σ + -X 2 Σ +) transitions of astrophysically significant BO molecule been reinvestigated. On the basis of the results it is concluded that the conventional Morse potential is not appropriate to yield meaningful information about the electronic transition moments. The preferential superiority of the RKRV potential over Morse potential in such studies has been critically discussed.

Intensity distribution in the bands of the D1 → X1∑ + system of PbO

Relative integrated intensities of the D1 → X 1∑ + system of PbO have been measured by heterochromatic photography photometry. The Morse potential has been employed to compute the Franck-Condon factors and r-centroids. The variation of electronic transition moment R e with internuclear separation r is found to be R e ( r) = const × (0.54 r − 1) in the range 1.957 ⩽ r, Å ⩽ 2.051. Relative band strengths are derived. The effective vibrational temperature of the source was 6199 K.

Franck-Condon factors,r-centroids and electronic transition moment variation with internuclear distance ofB 1Σ−X 1Σ band system of BeO using RKR potential

Franck-Condon factors,r-centroids and electronic transition moment variation with internuclear distance ofB 1Σ−X 1Σ band system of BeO using RKR potential

Electronic transition-moment variation in the [formula omitted] system of the AsO molecule

The spectrum of AsO was excited in a quartz discharge tube and the relative band intensities were measured by using photographic photometry. It was found that the electronic transition moment varies as R e ( r) = constant x (1–0.575 r) in the range 1.46 A ̊ < r < 1.66 A ̊ . Smoothed relative band strengths are derived for the 11 bands.

A study of variation of electronic transition moment of the B-X system of I2from its laser-excited fluorescence spectrum

Fluorescence in the B 3 Pi (0+u)-X 1 Sigma g+ system of I2 excited with 5145 AA radiation of an argon ion laser was recorded photoelectrically in the region 5200-8500 AA on a SPEX 0.85 m double monochromator. Using the measured intensities of P(17) rotational lines of thirty-eight ( nu '=43, nu ) bands and the Franck-Condon factors based on the recent molecular data of the B and X states, the variation of the square of the electron transition moment, mod M(R) mod 2, with R centroid in the range R=2.65-3.09 AA was studied. It was noticed that the electronic transition strength has a maximum value at R=2.83 AA and is represented by the relation mod M(R) mod 2=constant(-500.358+377.125R-38.483R2-25.429 R3+4.9831R4). Present results are discussed in relation to those obtained from earlier studies.

Relative band strengths from the study of intensity distribution in the A-X system of CrO

Relative integrated intensities are measured for ten bands in the vibrational structure of the astrophysically significant A 5π−X 5π system of CrO by the technique of photographic photometry. Vibrational transition probabilities are computed using the revised molecular constants of the electronic states. Using these results, the variation of electronic transition moment with the internuclear separation is found to be R e ( r) = const. × (1−0.398 r) in the range 1.60 A ̊ < r < 1.72 A ̊ . A smoothed array of band strengths is presented.

Electronic transition moment variation for the A 2Σ-X 2Π transition of the NO molecule

Two slightly differing techniques are proposed to determine the electronic transition moment variation R e( r) for the A 2Σ-X 2 Π transition of the NO molecule. A very slow variation of R e with internuclear distance r has been observed for this transition. Therefore within a small range of r, R e( r) is treated as a constant; its value is 0.135 atomic units.

Absolute absorption cross sections at high resolution in the A2Πi – X2Πi band system of ClO

Chlorine monoxide (ClO) has been produced at temperatures near 315 K in a fast-flow system at total pressures (of argon diluent) in the range 1.0–2.0 mm Hg. The transmittance of ultraviolet radiation has been determined with a spectral resolution of 0.0054 nm for all 35ClO ν′–0 A2Π3/2 – X2Π3/2 sub-bands in the range 3 ≤ ν′ ≤ 12 (305.9–274.9 nm). The ClO column density obtained with 8 or 12 traversals of the radiation along an 80 cm cell was in the range 1.0–2.0 × 1017 cm−2.The experimental transmittance profiles for each sub-band have been reproduced closely by synthetic spectrum calculations. The parameters required as input to the programs were optimized by nonlinear least-squares techniques. The fitted (Lorentzian) linewidths are on average more than double those previously reported from visual estimates of linewidths on photographic plates. The fitted band strengths lead to a well-defined electronic transition moment variation for the A – X system of ClO, which is in excellent agreement with an earlier determination by Mandelman and Nicholls from spectra at lower resolution (0.22 nm) with unresolved rotational structure.

Variation of electronic transition moment with the internuclear separation for the (AO +− X1Σ+) band system of PbO

Relative integrated intensities of the (AO +− X 1 Σ +) band system of PbO have been measured by photographic photometry. These have been interpreted with the aid of Franck-Condon factors ( q υ′ υ″ ) and r-centroids ( r υ′υ″ ) to show that the variation of electronic transition moment with internuclear separation is R e ( r)=const.(0.521 r−1). Arrays are shown for the band strengths S υ′ υ″ .

Franck—Condon factors,r-centroids and electronic transition moment variation with internuclear distance for AlO (A 2 Σ−X 2Σ) band system using RKR potentials

Franck—Condon factors,r-centroids and electronic transition moment variation with internuclear distance for AlO (A 2 Σ−X 2Σ) band system using RKR potentials

Intensity measurements and relative band strengths of the fluorescent bands of the (B-X) system of I 2

Relative integrated intensities of a few bands in the vibrational structure of the B-X fluorescent system of molecular iodine have been measured by the technique of photographic photometry. Reliable values of Franck-Condon factors and r-centroids given recently by Tellinghuisen have been employed to evaluate the variation of electronic transition moment with internuclear separation. The variation is found to be R e( r ̄ ) = const.(1−0.693 0r + 0.120 1r 2) in the range 2.76 < r < 2.81 Å. Smoothed arrays of band strengths are presented for the bands. The effective vibrational temperature of the source is found to be 340 ± 55 K.

On the E 1 Pi-X 1 Sigma + and 1 Sigma +-X 1 Sigma + transitions of ZrO related to S star spectra

view Abstract Citations (7) References (8) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the E 1 Pi-X 1 Sigma + and 1 Sigma +-X 1 Sigma + transitions of ZrO related to S star spectra Murty, P. S. Abstract Values of the Franck-Condon factors and r-centroids are obtained for the e 1 Pi-X 1 Sigma + (6495 A) and 1 Sigma +-X 1 Sigma + (5860 A) singlet band systems of ZrO in light of the detection of these bands in the spectrum of the pure S star R Cyg. A Morse potential function is used in the calculation of the Franck-Condon factors, while the values of the r-centroids, which are required for the study of the variation of electronic transition moment with internuclear separation, are calculated by the method of Nicholls and Jarmain (1956). Results suggest the possible presence of new band heads in both systems and indicate the usefulness of a reinvestigation of the spectrum in the 5500-6600 A region. Expected band head positions are presented for the new bands to aid in laboratory and stellar spectral studies. Publication: The Astrophysical Journal Pub Date: August 1980 DOI: 10.1086/158240 Bibcode: 1980ApJ...240..363M Keywords: Electron Transitions; Franck-Condon Principle; Line Spectra; S Stars; Stellar Spectra; Zirconium Oxides; Light Emission; Molecular Energy Levels; Spectral Bands; Transition Probabilities; Astrophysics full text sources ADS |

Vacuum UV emission by electronically-excited N 2: The radicative lifetime of the N 2(a′ 1Σ −u state

A measurement of the electronic transition moment variation for the N 2(a' 1Σ − uX 1Σ + g) band system has allowed a reassessment of the radiative lifetime of N 2(a′). Relaxation to N 2(a′,υ=0) is established as the major channel for quenching of N 2(a 1Π g, υ = 0) molecules by Ar.

Re-evaluation of electronic transition moment variation for D1Π−X1Σ of SnO

Franck-Condon factors andr-centroids have been computed for 18 bands ofD 1Π-X 1Σ transition of SnO molecule, using the realistic RKR potentials. The electronic transition moment variation with internuclear distance has been evaluated and this is represented by $$R_e \left( r \right) = const \times \left( {1 - 1.022r + 0.261r^2 } \right)$$ Franck-Condon factors andr-centroids ofDube andRai on Morse potential model are erroneous and hence fresh Morse calculations have been carried out. Also the vibrational temperature has been computed, both under constancy of electronic transition moment and under its variation. Allied parameters like oscillator strengths, Einstein coefficients etc. have been computed.

Electronic transition-moment variation in the A1π- X1Σ system of the GeO molecule

The spectrum of GeO was excited in a carbon arc and the relative band intensities were measured by using photographic photometry and were then interpreted in terms of Franck-Condon factors. It was found that the electronic transition moment varies as Re( r)=constant×(1-0.476 r-0.061 r 2), where 1.62⩽ r, Λ⩽1.82. Using this relation, smoothed band strengths, band-oscillator strengths and Einstein coefficients of the bands were calculated using expressions given by Penner. The effective vibrational temperature is estimated to be 1090 K. The average life times of the v′=0 and 1 vibrational levels have also been estimated.

Franck—Condon factors,r-centroids and electronic transition moment variation with internuclear distance of theA 1Σ−X 1Σ band system of BaO using RKR potentials

A comparative study of both RKR andMorse potentials as applied to AlO(A2Σ−X2Σ) band system has been made through various tests. Franck—Condon (FC) factors andr-centroids\(\bar r_{v'v''} \) with the use of RKR potential have been evaluated and have been employed to derive expressionRe(r) for electronic transition moment variation with internuclear distancer, 01 both by linear and quadratic fitting. Using suchRe(r) relations in conjunction with FC factors and also with experimental band strengths (I/vv′v″4, Smoothed Condon (Pv/t’v/t") factors andβ(=I/Pv/t’v/t"vv′v″4, the ratio of experimental band strength (I/vv/t’v/t"4 to the calculated Smoothed Condon (Pv/t’v/t") factor has been determined. Through the comparison ofPv/t’v/t"’s andβ’s of RKR potential and ofMorse potential, the efficacy ofMorse potential relative to RKR has been discussed. Vibrational temperatures for all the three thermal sources of excitation of bands, viz. Shock Tube, Low Pressure Arc and Exploding Wire have been deduced both under constancy ofRe and variation ofRe withr. These estimates on vibrational temperatures with the source temperatures have been discussed in the light of the findings ofLinton andNicholls and conclusions regarding relative merits of the two potentials indicated.

Intensity measurements in emission on 29 bands of the SO B3Σ--X3Σ-band system

Relative integrated emission intensity measurements have been made photoelectrically on the bands in the wavelength region 2580 AA to 4170 AA. These measurements have been interpreted with the aid of computed arrays of Franck-Condon factors and r-centroids to determine the variation of electronic transition moment with effective internuclear separation. A smoothed array of relative band strengths was thereby obtained. The array was placed on an absolute scale using radiative lifetime measurements of Smith (see abstr. A20137 of 1970) on the B3 Sigma state of SO. Arrays of Einstein A coefficients and band oscillator strengths are also presented for these bands.