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1.

The infrared part of the C₂ Phillips system (2.3–0.9 μm)

J Chauville J.P Maillard A.W Mantz 《Journal of Molecular Spectroscopy》1977,68(3):399-411

Line positions and molecular constants for the 0-0, 1-0, 2-0, 0-1, 2-1, 3-1, 0-2, 1-2, and 4-2 bands of the C₂ Phillips system (

A^{1} Π_{u} -X^{1} Σ_{g}^{+}

) are reported. Among them, five bands have not been reported previously. Rotational perturbations have been observed in the previously unobserved v = 1 level of the

A^{1} Π_{u}

state. This state is perturbed by the

c^{3} Σ_{u}^{+}

state which was discovered by Ballik and Ramsay. These observations provide new information regarding the perturbing state. In particular, the minimum of the potential energy for the

c^{3} Σ_{u}^{+}

state has been found to be at 9227.4 cm^?1 instead of 13 310 cm^?1, which was the previous T_e value for this electronic state. 相似文献

2.

Spectrum and structure of the He2 molecule: Characterization of the singlet and triplet states associated with the UAO's 4s, 4dσ, 4dπ, and 4dδ

C.M Brown M.L Ginter 《Journal of Molecular Spectroscopy》1973,46(2):256-275

The emission spectrum of the He₂ molecule has been rephotographed in the ～4000–～5700 Å region and the

4d(^{3} Σ_{u}^{+},^{3} Π_{u},^{3} Δ_{u}) → 2pπ^{3} Π_{g}

,

4d(^{1} Σ_{u}^{+},^{1} Π_{u},^{1} Δ_{u}) → 2pπ^{1} Π_{g}

,

4s^{3} Σ_{u}^{+} → 2pπ^{3} Π_{g}

and

4s^{1} Σ_{u}^{+} → 2pπ^{1} Π_{g}

transitions analyzed. The 4dδj³Δ_u, 4dπj³Π_u,

4dσj^{3} Σ_{u}^{+}

and

4sh^{3} Σ_{u}^{+}

states have been characterized through v = 2 and the 4dδJ¹Δ_u, 4dπJ¹Π_u,

4dσJ^{1} Σ_{u}^{+}

, and

4sH^{1} Σ_{u}^{+}

states for v = 0. The term levels for these perturbed and l-uncoupled states have been confirmed (a) by analyses of bands with common levels from Δv = 0, ±1 sequences and (b) by analyses of the transitions between the above states from 4d and 4s and the

c^{3} Σ_{g}^{+}

and

C^{1} Σ_{g}^{+}

states associated with 3pσ. Molecular constants are reported which have been partially corrected for the effects of l-uncoupling and the homogeneous perturbations between the state pairs J, H and j, h. 相似文献

3.

Spectrum and structure of the He₂ molecule: Characterization of the triplet states associated with (1σ_g)²(1σ_u)nsσ, ndσ, ndπ, and ndδ (n = 5–12)

D.S Ginter M.L Ginter 《Journal of Molecular Spectroscopy》1983,101(1):139-160

Emission spectra for the electronic transitions

ndλ(^{3} Σ_{u}^{+},^{3} Π_{u},^{3} Δ_{u}) → 2pπ b^{3} Π_{g} (n = 5–12)

,

nsσ^{3} Σ_{u}^{+} → 2pπ b^{3} Π_{g} (n = 5–12)

,

ndλ(^{3} Σ_{u}^{+},^{3} Π_{u},^{3} Δ_{u}) → 3pσ c^{3} Σ_{g}^{+} (n = 5–10)

,

nsσ^{3} Σ_{u}^{+} → 3pσ c^{3} Σ_{g}^{+} (n = 5–11)

,

ndλ(^{3} Σ_{u}^{+},^{3} Π_{u},^{3} Δ_{u}) → 3pπ e^{3} Π_{g} (n = 6–11)

,

nsσ^{3} Σ_{u}^{+} → 3pπ e^{3} Π_{g} (n = 6–11)

,

nsσ^{3} Σ_{u}^{+} → 4pσ g^{3} Σ_{g}^{+} (n = 9–11)

, and

10dδ^{3} Δ_{u} → 4pσ g^{3} Σ_{g}^{+}

of ⁴He₂ are reported and the electronic structure of the triplet states associated with v = 0 of (1σ_g)²(1σ_u) nsσ and ndλ characterized. The energy levels comprising the

(1σ_{g})^{2} (1σ_{u})ndλ(^{3} Σ_{u}^{+},^{3} Π_{u}^{+},^{3} Δ_{u}^{+})

and the

(1σ_{g})^{2} (1σ_{u})ndλ(^{3} Π_{u}^{?},^{3} Δ_{u}^{?})

manifolds exhibit strong channel mixing, while the mixing of the

(1σ_{g})^{2} (1σ_{u})nsσ^{3} Σ_{u}^{+}

with the

nd(^{3} λ Σ_{u}^{+},^{3} Π_{u}^{+},^{3} Δ_{u}^{+})

channel structure is relatively minor. Models based on multichannel quantum defect theory are used to aid in the spectral assignments and to correlate the observed level structures. We show that three-limit and two-limit models adequately represent the bulk of the observed

ndλ(^{3} Σ_{u}^{+},^{3} Π_{u}^{+},^{3} Δ_{u}^{+})

and

ndλ(^{3} Π_{u}^{?},^{3} Δ_{u}^{?})

channel structures, respectively. 相似文献

4.

Laser-excited phosphorescence spectrum of C₃S₂ in an Ar matrix

H. Takeuchi M. Tasumi 《Journal of Molecular Spectroscopy》1981,90(1):116-128

The phosphorescence spectrum of C₃S₂ was observed in a low-temperature Ar matrix with excitation of an Ar⁺ laser. The spectrum consists of a very strong 0-0 band at 18 287 cm^?1 and well-resolved progressions in the ν₂, ν₅, ν₆, and ν₇ vibrations. Side bands were found on the high-energy sides of some transitions. The separation between the main and side bands is 23 cm^?1. Polarization analysis suggests that C₃S₂ is linear symmetric in the Phosphorescent state as in the ground electronic state. On the basis of symmetry considerations and a qualitative evaluation of spin-orbit coupling, the phosphorescent state is assigned to ³Σ_u^? with Σ_u⁺ and Π_u components split by spin-spin interaction. The Σ_u⁺ level is lower than the Π_u one by 23 cm^?1 and the main and side band emissions start from the Σ_u⁺ and Π_u levels, respectively. The Σ_u⁺ component seems to acquire allowed character from a ¹Σ_u⁺ state by spin-orbit coupling and from bent

^{1} Σ_{g}^{?} (^{1} B_{2})

and

^{1} Δ_{g} (^{1} A_{1} +^{1} B_{2})

states by ν₅ vibronic coupling. Mixing of the Σ_u⁺ and Π_u components through ν₅ is responsible for most of the side bands. The ν₅ frequency is estimated to be 160 ± 20 cm^?1 in the ³Σ_u^? state from the intensities of ν₅ progression bands and from the ground-state frequency, 411 cm^?1. 相似文献

5.

3Σu−-3Σu+ coupling in the O2B3Σu− predissociation

Paul S. Julienne 《Journal of Molecular Spectroscopy》1976,63(1):60-79

The role of

B^{3} Σ_{u}^{?} -2^{3} Σ_{u}^{+}

spin-orbit mixing in the O₂ Schumann-Runge predissociation is investigated. The

2^{3} Σ_{u}^{+}

state is found to cross the

B^{3} Σ_{u}^{?}

state near 2.0 Å with an interaction matrix element of approximately 55 cm^?1. This state contributes to the widths of the Bv ≥ 6 levels, but introduces only small level shift perturbations. When the partial widths due to the

^{3} Σ_{u}^{?} -^{3} Σ_{u}^{+}

interaction are added to the previously calculated widths due to the ⁵Π_u, ³Π_u, and ¹Π_u states, reasonable agreement is obtained with experimental measurements on O¹⁶O¹⁶ and O¹⁸O¹⁸. The possibility of non-Lorentzian line profiles and the dependence of the width on rotational quantum number is investigated. The approximation of the spin-orbit matrix element by its value at the crossing point is shown to be a good approximation for calculating the second difference perturbations. 相似文献

6.

Acetylene fluorescence

L.E. Brus 《Journal of Molecular Spectroscopy》1979,75(2):245-250

Previously unobserved acetylene

^{1} A_{u} (^{1} Σ_{u}^{?}) →^{1} Σ_{g}^{+}

fluorescence occurs following 1933-Å ArF laser excitation of C₂H₂ or C₂H₄ and their deuterated analogs in solid Ne and Ar hosts at 4.2 K. Acetylene is a photolysis product of matrix-isolated ethylene. Ground-state vibrational levels as high as ν″₃ = 30 of the degenerate ν₃ bending vibration are observed for C₂D₂. Only ν₃ is appreciably active in the fluorescence. The negative ν₃ anharmonicity, previously observed in the gas phase, also occurs in Ne host. Consideration of rotational selection rules indicates that the Ne host strongly hinders free rotation about the low-moment-of-inertia

a ?

axis in the excited state. 相似文献

7.

Lifetime of electronic states of CO₂⁺

C Herran F Arqueros J Campos 《Journal of Molecular Spectroscopy》1983,97(2):244-247

The radiative lifetimes of the

A ?^{2} Π_{u}

and

B ?^{2} Σ_{u}^{+}

states of CO₂⁺ were measured by means of the delayed coincidence method. Excitation was performed by a pulsed electron beam incident on CO₂. The results of these measurements are 115 ± 5 nsec for the

A ?^{2} Π_{u}

state and 126 ± 3 nsec for the

B ?^{2} Σ_{u}^{+}

state. 相似文献

8.

N2+ bound quartet and sextet state potential energy curves

Harry Partridge Charles W. Bauschlicher James R. Stallcop 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,33(6):653-655

Potential energy curves for the

^{4} Σ^{+}_{u}

,

^{4} Π_{g}

and

^{6} Σ^{+}_{g}

states of N⁺₂ that dissociate to N (

^{4} S^{0}

) and

N^{+} (^{3} P)

, have been determined from a complete active space self-consistent field calculation. The

^{6} Σ^{+}_{g}

state is found to be significantly bound (D_e = 2.68 eV) with a minimum at 1.72 Å. 相似文献

9.

The spectrum and structure of the He2 molecule: Characterization of the triplet states associated with the UAO's 4pσ, 5pσ, and 6pσ

F.B. Orth M.L. Ginter 《Journal of Molecular Spectroscopy》1976,61(2):282-288

The emission spectrum of the He₂ molecule has been rephotographed in the ～3200–4100 Å region and the

4pσ g^{3} Σ_{g}^{+} → 2s a^{3} Σ_{u}^{+}

,

5pσ k′^{3} Σ_{g}^{+} → 2s a^{3} Σ_{u}^{+}

, and

6pσ n^{3} Σ_{g}^{+} → 2s a^{3} Σ_{u}^{+}

transitions analyzed. The g, k′, and n states, which have not been reported previously, are characterized through v = 1, 2, and 1, respectively. Several small accidental perturbations have been observed in the rotational manifolds of the k′ and n states. 相似文献

10.

Laser excitation spectra of He₂

Terry A. Miller V.E. Bondybey 《Journal of Molecular Spectroscopy》1979,78(1):120-124

Metastable

a(2sσ)^{3} Σ_{u}^{+}

He₂ molecules are produced by a dc discharge in a flowing He stream. Laser excitation downstream of the discharge produces excitation spectra for a number of He₂ states. LIF spectra are observed for the

(npπ)^{3} Σ_{g}^{+}

series for n = 4–9, excepting 5 and the

(npπ)^{3} Π_{g}

series for n = 5–15. 相似文献

11.

Energy levels of low lying triplet states of N₂ from infrared emission studies

E.J. Beiting C.C. Jones W. Benesch 《Journal of Molecular Spectroscopy》1978,70(1):108-123

A theoretical model used to describe the

B′^{3} Σ_{u}^{?}

and B³Π_g states of N₂ is presented. Using recently acquired high resolution spectra of the

B′^{3} Σ_{u}^{?} → B^{3} Π_{g}

(0-0) band, rotational energy levels of the v = 0 vibrational levels of these two states are generated with this model. These levels are in excellent agreement with those obtained using a combination differences technique. The precision of the model generated levels is 0.01 cm^?1. The previously unpublished rotational levels of Dieke and Heath for the

A^{3} Σ_{u}^{+}

, B³Π_g and C³Π_u states are referenced to the

N_{2} X^{1} Σ_{g}^{+}

(v = 0, J = 0) ground level and tabulated here. Estimates of the precision of their work are made. 相似文献

12.

Model calculation of the electronic structure and spectroscopy of Hg₂

F.H. Mies W.J. Stevens M. Krauss 《Journal of Molecular Spectroscopy》1978,72(3):303-331

Energy curves and transition moments of the excited valence states of Hg₂ were obtained in a model calculation based on calculated Mg₂ energy levels and the assumption that the asymptotic spin-orbit matrix elements for the Hg atom are applicable to the molecular states. The spin-orbit and orbital-rotational interaction of the excited states of Hg₂ is analyzed in both a Hund's case (c) and (a) representation. The intermediate (a) → (c) transition moments are obtained as a function of the internuclear distance. The effect of the orbital-rotational interaction which introduces Hund's case (b) and (e) couplings is found to be small for transitions among excited states under the conditions normally encountered for populating excimer states.Using the energy level positions and transition moments, the observed spectra and predicted spectra are compared for both radiative transitions including the ground state and among the excited states. The lifetime of the

1_{u} (^{3} Σ_{u}^{+})

excimer state is calculated to be 1.4 μsec with the 335 nm band assigned to the

1_{u} → X^{1} Σ_{g}^{+}

transition. The 485 nm bands cannot be assigned to any Hg₂ transitions. Strong bound-continuum absorptions are predicted for the 485 nm bands. On the other hand, the 335 nm emission is predicted to be absorbed by bound-bound transitions only. 相似文献

13.

Predissociation and Λ-doubling in the even-parity Rydberg states of the nitrogen molecule

Robert S. Mulliken 《Journal of Molecular Spectroscopy》1976,61(1):92-99

Predissociations in the y¹Π_g and

x^{1} Σ_{g}^{?}

Rydberg states of N₂ (configurations

1π_{u}^{?1} 4pσ

and

1π_{u}^{?1} 3pπ

, respectively) and their likely causes, are discussed. Peaking of rotational intensity at unusually low J values, without sharp breaking off, is interpreted as due to case c^? or case cⁱ predissociation. Λ doubling in the y state, attributed to interactions with the

x^{1} Σ_{g}^{?}

state and with another, ¹Σ⁺, state of the same electron configuration as x, is analyzed. From this analysis the location of the (unobserved)

^{1} Σ_{g}^{+}

state, here labeled x′, is obtained. It is concluded that the predissociation in the Π⁺ levels of the y state is an indirect one mediated by the interaction with x′ coupled with predissociation of x′ by a

^{3} Σ_{g}^{?}

state dissociating to

^{4} S +^{2} P

atoms: combined, however, with perturbation of the y state by the k¹Π_g Rydberg state (configuration

3σ_{g}^{?1} 4dπ

), whose Π⁺ levels are completely predissociated. 相似文献

14.

Energies and orbital sizes for some Rydberg and valence states of the nitrogen molecule

Walter C. Ermler Robert S. Mulliken 《Journal of Molecular Spectroscopy》1976,61(1):100-106

Accurate SCF computations are reported on the Rydberg states of N₂ of electron configurations

---1π_{u}^{3} 2π_{u}

,

---1π_{u}^{3} 3σ_{u}

, and ---3σ_g2π_g, also on the valence states of the configuration

---1π_{u}^{3} 1π_{g}

. The Rydberg state calculations supplement those of Lefebvre-Brion and Moser. A comparison is made between the

---1π_{u}^{3} 2π_{u}

states and the parallel set of states of the

1π_{u}^{3} 1π_{g}

configuration. This comparison shows a sharp difference in the ¹Σ⁺ states of the two configurations, the ¹Σ⁺ state being very high in the latter but relatively low in the former configuration. Recknagel coefficients are given for the several states of the two configurations; as expected, these are much smaller for the

1π_{u}^{3} 2π_{u}

configuration. Also, the ¹Δ state is relatively lower for the latter configuration. 相似文献

15.

The spectrum and structure of the He2 molecule: Multichannel quantum defect analyses of the triplet levels associated with (1σg)2(1σu)npλ

Dorothy S Ginter Marshall L Ginter 《Journal of Molecular Spectroscopy》1980,82(1):152-175

Emission spectra for the electronic transitions

6–17pπ^{3} Π_{g} -2s a^{3} Σ_{u}^{+}

and

7–16pσ^{3} Σ_{g}^{+} -2s a^{3} Σ_{u}^{+}

of He₂ are reported and the electronic structures of

npπ^{3} Π_{g}^{?}

and

np(^{2} Σ_{g}^{+},^{3} Π_{g}^{+})

characterized. The energy levels associated with

(1σ_{g})^{2} (1σ_{u})np(^{3} Σ_{u}^{+},^{3} Π_{g}^{+})

exhibit extensive channel mixing, which leads to a breakdown of conventional band models for the higher n¹-members of these Rydberg “series.” However, a model based on multichannel quantum defect theory quantitatively correlates the observed level structures. The higher-energy (

n^{1} > ～5

) portions of the

np(^{3} Σ_{g}^{+},^{3} Π_{g}^{+})

channels can be represented by two eigen-quantum defects μ₁ = 0.225 and μ₂ = 0.930 and the close- to loose-coupling matrix elements

U_{11} = U_{22} = [N(2N + 1)^{?1}]^{12}

and

U_{12} = ?U_{21} = [(N + 1)(2N + 1)^{?1}]^{12}

. The inclusion of energy dependence in the μ_α's leads to quantitative correlations for all n¹-values. 相似文献

16.

Molecular three-body approach to

_{Λ}^{9} Be

and

_{Σ}^{9} Be

hypernuclei

J. Révai J. Žofka 《Physics letters. [Part B]》1981,101(4):228-232

The dependence of the low-lying spectra of

_{Λ, Σ}^{9} Be

hypernuclei on hyperon-α interaction in the molecular α + α + Λ(Σ) scheme has been studied. A suggestion is made for obtaining the strengths of both p-wave and spin-orbit Λ-α interactions from the experimental

_{Λ}^{9} Be

spectrum. A relation between the Σ⁰-binding energies

B_{Σ} (_{Σ}^{9} Be)

and

B_{Σ} (_{Σ}^{9} He)

has been established and on its basis a prediction is made about a possible binding energy of

_{Σ}^{5} He

. 相似文献

17.

The spectrum of HeNe⁺

I. Dabrowski G. Herzberg 《Journal of Molecular Spectroscopy》1978,73(2):183-214

Discharges through mixtures of helium and neon show two band groups near 4250 and 4100 Å as first observed by Druyvesteyn. These bands, assigned to the HeNe⁺ ion by Tanaka, Yoshino, and Freeman, have been studied under high resolution and have been fairly completely analyzed. The upper state of the transition is a very weakly bound state resulting from

He^{+} (^{2} S) + Ne (^{1} S_{0})

. There are two lower states resulting from the two components of

Ne^{+} (^{2} P) + He (^{1} S_{0})

. The upper of these two (

^{2} Π_{12}

) is also very weakly bound while the lower of the two, the ²Σ⁺ ground state, has a dissociation energy of 0.69 eV and an r_e value of 1.30 Å. All bands in both band groups show four branches designated R_ff, Q_ef, Q_fe, and P_ee. From their analysis the rotational constants in the various vibrational levels of the three electronic states have been determined. While no spin splitting in the B²Σ⁺ state has been found the ground state X²Σ shows a very large spin splitting and the

A_{2}^{2} Π_{12}

state a very large

Ω-type

doubling. The vibrational numberings in all these states were established by the study of the spectrum of ³HeNe⁺. At the same time the hyperfine structure observed in all lines of ³HeNe⁺ confirmed the nature of the upper state B²Σ⁺ as resulting from He⁺ + Ne, i.e., by charge exchange from the ground state. The

^{2} Π_{12}

component of the ²Π state has not been observed, presumably because of low intensity. 相似文献

18.

Hyperfine spectra of bromine vapor near 633 nm

R.S. Eng J.T. LaTourrette 《Journal of Molecular Spectroscopy》1974,52(2):269-276

The hyperfine spectra of the (17-7)P(57) line of ⁷⁹Br₂ and the (12-4) P(129) line of ⁸¹Br₂, both of the

B^{3} Π_{0^{+}u} ← X^{1} Σ_{g}^{+}

electronic transition near 633 nm have been measured by the saturated absorption method. An analysis based on nuclear quadrupole and spin-rotation interactions is presented. 相似文献

19.

Formation of Xe¹₂ by collision pair absorption at 158 nm

H.P. Grieneisen K. Hohla K.L. Kompa 《Optics Communications》1981,37(2):97-99

Pair absorption from colliding Xe atoms of the molecular fluorine laser radiation is reported. The absorption coefficient for this process at 300 K was found to be α = (4.32 ± 0.1) × 10^-9Torr^-2cm^-1. Fluorescence at 172 nm originating predominantly from the

^{1} Σ^{+}_{u}

state of Xe¹₂ indicates that by this mechanism the Xe dimer laser can be pumped optically. 相似文献

20.

Molecular Rydberg transitions: Cyanogen chloride

W.S. Felps S.P. McGlynn G.L. Findley 《Journal of Molecular Spectroscopy》1981,86(1):71-85

The electronic absorption spectrum of cyanogen chloride has been investigated in the range 2200-1250 Å. The first s-Rydberg transitions,

X ?^{1} Σ^{+} →^{3} Π_{1}

and

X ?^{1} Σ^{+} →^{1} Π_{1}

have been assigned, and analyzed to yield exchange and spin-orbit coupling parameters. The relative intensities of these two transitions have been shown to accord with an intermediate coupling situation. The

π → π^{1}

intravalence excitations, leading to ^1.3(Σ^?, Δ and Σ⁺) states, have been discussed. It has been shown that one or both of the ¹Σ^? and ¹Δ states have bent geometries and that the ¹Σ⁺ state is located (tentatively) at 79 755 cm^?1. Two

σ → π^{1} π → σ^{1}

states have been assigned, one at 56 340 cm^?1, the other at 74 450 cm^?1. The latter assignment is tentative, being largely based on observed vibronic interferences between the

X ?^{1} Σ^{+} →^{1} Π_{1}

transition and the 74 450 cm^?1 transition. A considerable amount of vibrational oscillator strength and quantum defect data is presented. 相似文献