Optical-optical Double Resonance Spectroscopy Research Articles

The 5 1Σ+g and 6 1Σ+g States of 39K2 Studied by Optical-Optical Double Resonance Spectroscopy

The molecular constants of the previously unobserved 5 and 6 1Σ+g states of K2 are determined and the potential curves are constructed using the Rydberg-Klein-Rees (RKR) method. The absolute vibrational numbering of the 5 1Σ+g state is obtained by comparing the intensities of resolved fluorescence spectra with calculated Franck-Condon (FC) factors.

Rotational structure of the B–X system of Na3 from high-resolution resonant two-photon ionization spectroscopy

First investigations of the [Formula: see text] system of Na3 at rotational resolution are reported. Using resonant two-photon ionization and optical-optical double resonance spectroscopy, two vibronic bands were assigned and rotationally analyzed. In the B state, the three sodium nuclei perform a nearly free pseudorotational motion in the moat of a pseudo-Jahn–Teller potential that is characterized by a vibronic angular momentum quantum number j. In states with J > 0, each rotational level is split by Coriolis interaction. Rotational and Coriolis coupling parameters were determined and are discussed in terms of the dynamics of the vibronic coupling in this floppy molecule.

Optical-Optical Double Resonance Spectroscopy of the 6 1Σ +g Shelf State of Na 2 Using an Ultrasensitive Ionization Detector

The Na 2 6 1Σ + g state has been observed from v = 0 to v = 39 by using optical-optical double resonance spectroscopy and an ultrasensitive ionization detector. The molecular constants and the Rydberg-Klein-Rees (RKR) potential energy curve are presented in this paper. Eigenvalues calculated from the ab initio potential [S. Magnier et al., J. Chem. Phys. 98, 7113-7125 (1993)] are also discussed.

Optical-Optical Double-Resonance Spectroscopy of Cl 2: Analyses of the 0 +u, 1 u, and 2 u( 3P2) Ion-Pair States

The optical-optical double-resonance spectroscopy is applied to study the ion-pair states of Cl 2 correlating to Cl −( 1 S) + Cl +( 3 P 2). In the (1 + 2) photoexcitation sequence, we gain access to the 0 + u( 3 P 2) and 1 u( 3 P 2) ion-pair states through the A 3Π(1 u) and B 3Π(0 + u) states as intermediates. These states are found to lie closely together and show strong heterogeneous coupling with each other. The transitions to the nearby 2 u( 3 P 2) state are first noticed as extra lines through the mixing with the 1 u( 3 P 2) state, and the observations are extended by the perturbation-facilitated optical-optical double-resonance technique. The energy levels of the 0 + u, 1 u, and 2 u( 3 P 2) states are analyzed in detail by including the heterogeneous interaction between these states. The electronic structures of the ion-pair states are discussed. These results allow us to map out the ion-pair states and to clear up the puzzle of previously observed states in the 7-eV region.

Measurements of the radiative lifetimes of the Cl 2 ion-pair states by optical-optical double resonance

The technique of optical-optical double resonance spectroscopy is used to study the radiative lifetimes of the Cl 2 ion-pair states from the fluorescence decays. This experiment allows us to classify the six gerade states correlating to the lowest asymptote Cl −( 1S)+Cl +( 3P) into two groups from the fluorescence lifetimes. One involves the four spin-orbit components of the 3Π g state, O + g( 3P 2), O − g( 3P 2), 1 g( 3P 2), and 2 g( 3P 2), showing short lifetimes of 4–5 ns. The other includes those of 3Σ − g with lifetimes almost an order of magnitude longer; 44.6±0.5 ns for 0 + g( 3P 0) and 73.8±3.0 ns for 1 g( 3P 1).

Spectroscopic Study of the Na 2 2 3Σ +g State by cw Perturbation-Facilitated Optical-Optical Double-Resonance Spectroscopy

The Na 2(3 sσ g )(4 sσ g ) 2 3Σ + g state of Na 2 has been observed and studied by cw perturbation-facilitated optical-optical double-resonance (PFOODR) spectroscopy for the first time. A single-mode dye laser and a Ti-sapphire laser served as the pump and the probe lasers, respectively. A total of 543 PFOODR excitation signals have been assigned to the 2 3Σ + g ← b 3Π 1u transitions. Absolute vibrational numbering was determined by counting nodes in the 2 3Σ + g → a 3Σ + u bound-free spectra. Spectroscopic constants and the corresponding RKR potential energy curve are presented in this vsork. The values of T e, R e, and D e, are found to be 25 551.237(49) cm −1, 3.53463(35) Å, and 6211.5(1) cm −1 respectively.

The study of the 39K 2 Rydberg 1Δ g states by CW optical-optical double-resonance spectroscopy

Three intermediate-lying Rydberg 1Δ g states of 39K 2 were studied by CW optical-optical double-resonance (OODR) spectroscopy. The absolute vibrational numbering, the Dunham coefficients, the Rydberg-Klein-Rees (RKR) potential curves, and the Franck-Condon factors (FCF) of three ( nd) 1Δ g - B 1Π u systems are given. The variation with the principal quantum number n of the contribution of the ndδ g Rydberg electron to the binding energy is discussed. In addition, five observed successive ( nd) 1Δ g states included in this work ( n = 8, 9, and 10) and the work of Wang et al. ( J. Chem. Phys., in press) ( n = 6 and 7) are assigned absolute electronic state numbering based on the molecular building-up principle. Furthermore, the dissociation limits, the dissociation energies, and the quantum defects of those ( nd) 1Δ g states are compared with respect to the asymptotic assignments made by Broyer et al. ( Chem. Phys. Lett. 99, 206–212, 1983) and by Kowalczyk et al. ( Z. Phys. D. 13, 231–240, 1989); our work supports the assignment of Broyer et al.

The Na 2 2 3Δ g state: CW perturbation-facilitated optical-optical double resonance spectroscopy

The Na 2 ( σ g 3 s)(4 dδ g ) 2 3Δ g state has been studied by CW sub-Doppler perturbation-facilitated optical-optical double resonance (PFOODR) spectroscopy. Twenty-three vibrational levels have been observed with resolved fine-hyperfine structure. The fine-hyperfine coupling scheme of the 2 3Δ g state is exactly the same as the Na 2 ( σ g 3 s)(3 dδ g ) 1 3Δ g : case b βs coupling with Fermi contact constant b = 221.7 MHz. Absolute vibrational numbering of the 2 3Δ g state has been determined from the PFOODR fluorescence to the b 3Π u state. The Dunham coefficients were then derived and the corresponding RKR potential curve was determined.

Optical-optical double resonance spectroscopy of Cl 2: Absolute position of the lowest-lying [formula omitted] ion-pair state

The optical-optical double resonance spectroscopy is applied to determine the absolute position of the lowest-lying 2 g( 3P 2) ion-pair state of Cl 2. The X 1Σ g + ground state is optically combined with the 2 g( 3P 2) state through the A 3Π(1 u ) ∼ A′ 3Π(2 u ) interacting state: The pump laser excites the molecules to the intermediate state through its A 3Π(1 u ) property. The probe laser executes the second step of excitation through the A′ 3Π(2 u ) character of the intermediate state, because the ΔΩ = 0 selection rule holds for the valence to ion-pair state transitions possessing a charge transfer property. A set of Dunham parameters of the 2 g( 3P 2) state is determined from a global least-squares fit analysis of 429 transitions in the v′ = 0 ∼ 20 and J′ = 9 ∼ 50 ranges: Y 00 = 57 295.722(5), Y 10 = 252.3454(13), Y 20 = −1.007 08(12), Y 30 = 2.2286(33) × 10 −3, Y 01 = 0.116 673 9(44), Y 11 = −6.4662(48) × 10 −4, Y 21 = 9.48(23) × 10 −7, and Y 02 = −1.020(14) × 10 −7 (all in cm −1 and σ in parentheses).

Optical-optical double resonance spectroscopy of Cl 2: Analysis of the A3Π(1 u)- X1Σ g+ system

The A 3Π(1 u )- X 1Σ g + absorption system of Cl 2 is studied by optical-optical double resonance using the 1 g( 3P 2)-A 3 Π(1 u)-X 1 Σ g + photo-excitation sequence: We label a particular level of the intermediate A 3Π(1 u ) state through the 1 g( 3P 2)-A 3 Π(1 u) transition and extract this system from the visible absorption spectrum which contains the much stronger B 3Π(0 u +)- X 1Σ g + system in the same region. The vibrational bands of 35Cl 2, with 2≦ v′≦13 and 1≦ J′≦51, are measured to within 0.02 cm −1 and rotationally analyzed by including the heterogeneous interactions with other bound states, A′ 3Π(2 u ), B′ 3Π(0 u −), and B 3Π(0 u +). The intensity anomaly found in the transitions to the interacting A 3Π(1 u ) and B 3Π(0 u +) states is interpreted as an interference effect between parallel ( B- X) and perpendicular ( A- X) transition amplitudes, whose ratio ( μ | e μ ⊥ e ) is determined to be 4.8.

The Na 2 4 1Σ g+ ∼ 2 3Π g ∼ 1 3Δ g triple perturbation: Deperturbation of the ( vΣ, vΠ, vΔ) = (6, 2, 7) and (7, 3, 8) interactions

Two examples of the 4 1Σ g + ∼ 2 3Π g ∼ 1 3Δ g triple perturbation were observed by cw dye laser optical-optical double resonance spectroscopy via the A 1Σ u + v′ = 5 intermediate state. The ( v Σ, v Π, v Δ) = (6, 2, 7) and (7, 3, 8) perturbation complexes were deperturbed, yielding the following molecular constants: T 2 (2 3Π g) = 29027.102 (10) cm −1 , ΔG 5 2 (2 3Π g) = 92.206 (10) cm −1 , A (2 3Π g) = 4.06 (1) cm −1 , B 2 (2 3Π g) = 0.073740 (16) cm −1 , T 7 (1 3Δ g) = 28979.385 (15) cm −1 , ΔG 15 2 (1 3Δ g) = 122.450 (25) cm −1 , B 7 (1 3Δ g) = 0.117243 (20) cm −1 , T 6 (4 1∑ + g ) = 29010.357 (31) cm −1 , ΔG 13 2 (4 1∑ + g ) = 101.096 (44) cm −1 , B 6 (4 1∑ + g ) = 0.087626 (19)cm −1 and perturbation parameters: ζ(4 1∑ + g ∼ 2 3Π g 〈 υ ∑ | υ π〉 = 1.459 (16) cm − 1 at R c = 4.64 A ̊: , α(2 3∑ + g ∼ 1 3Π g 〈 υ π | υ δ〉 = 0.16 (7) cm − 1 at R c = 4.12 A ̊: , β(2( 3Π g ∼ 1 3 Δ g) lang;υ π | B (R) | υ δ〉 = 0.648 (20) A ̊: In addition, the hyperfine structure of the 2 3Π g v = 2 level was sampled for all three Ω-components and many J-values. The hyperfine structure of the case a β 2 3Π g state is very similar to that in the b 3Π u state and, like all singly excited triplet states of Na 2, is dominated by the Fermi contact contribution from the singly occupied σ g (3 s) valence orbital.

An optical-optical double resonance spectroscopy of bromine through the A3.PI.(1u) state: analyses of the Ou+, 1u, and 2u(3P2) ion-pair states

An optical-optical double resonance technique is used to study the ion-pair states of Br 2 correlating to Br − ( 1 S)+Br + ( 3 P 2 ). In the (1+2) photoexcitation sequence, the pump laser excites the A 3 II(1 u )−X 1 ∑ g + transition at a fixed frequency for the state selection while the probe laser is scanned to execute the second step by a coherent two-photon transition

Optical-optical double resonance spectroscopy of the Na 2 2 1Π g state

The Na 2 2 1Π g state has been observed from v = 0 to v = 43 (80% of the well depth) by using optical-optical double resonance spectroscopy. The Dunham coefficients and the Rydberg-Klein-Rees (RKR) potential energy curve are presented in this paper.

Optical-optical double resonance spectroscopy of the 1 g( 3P 2)-A 3Π(1 u)-X 1Σ g+ transition of Cl 2

We describe the results of optical-optical double-resonance spectroscopy of Cl 2 on the 1 g( 3P 2)←( hv 2)-A 3Π(1 u) ←( hv 1)-X 1Σ g + transition. The state-selective transition from the ground state of Cl 2 to the A 3Π(1 u) state was observed by scanning the pump laser ( hv 1) frequency, while fixing the probe laser frequency ( hv 2) to the 1 g( 3P 2)-A 3Π(1 u) system. In this procedure, a rotational analysis on the A 3Π(1 u)-X 1Σ g + system is made on several vibrational bands for two isotopic species, 35Cl 35Cl and 37Cl 35Cl, and the vibrational numbering is determined from the isotope difference. The 1 g( 3P 2)-A 3Π(1 u) system is also analyzed to establish the absolute position of the 1 g( 3P 2) ion-pair state.

Two-colour dip spectroscopy of jet-cooled molecules

Abstract In optical-optical double resonance spectroscopy, the resonance transition from an intermediate state to a final state can be detected by a dip of the signal (fluorescence or ion) associated with the intermediate state. This method probing the signal of the intermediate state may be called ‘two-colour dip spectroscopy’. Various kinds of two-colour dip spectroscopy such as two-colour fluorescence/ion dip spectroscopy, two-colour ionization dip spectroscopy employing stimulated emission, population labelling spectroscopy and mass-selected ion dip spectroscopy with dissociation were briefly described, paying special attention to their characteristics in excitation, detection and application. They were extensively and successfully applied to jet-cooled large molecules and provided us with new useful information on the energy and dynamics of excited molecules.

Hyperfine structure of the Na 2 1 3Δ g state

The hyperfine structure in the Na 2 1 3Δ g state is partially resolved by perturbation facilitated optical-optical double resonance (PFOODR) spectroscopy via A 1Σ u + ∼ b 3Π u mixed intermediate levels. The hyperfine splitting and intensity patterns are shown to be consistent with the Hund's case b βS limit, which implies that J-destroying hyperfine matrix elements are large relative to all fine structure splittings. The fine and hyperfine splitting in the 1 3Δ g state is dominated by the Fermi contact coupling constant associated with the σ g 3 s valence orbital. The fitted coupling constant, b = 210 ± 8 MHz, agrees well with a simple prediction, 221 MHz, based on the atomic Na 3 2 S Fermi contact constant. We suggest that all nlλ 3Λ triplet Rydberg states of Na 2 and Li 2, built on the X 2Σ g + ion-core ground state, will exhibit case b βS limiting behavior with fine and hyperfine structure dominated by an n,l,λ-independent Fermi contact coupling constant.

Fluorescence-detected optical-optical double resonance spectroscopy of Rydberg-Rydberg transitions in NO

Fluorescence-detected optical-optical double resonance (OODR) spectroscopy is used to determine the relative transition intensities from the 3pπ C 2Π, ν′=0 state to the n*= 6 supercomplex of NO. The results are in good agreement with the multi-channel quantum defect theory analysis of Fredin et al. (Mol. Phys. 60 (1987) 825) and support their conclusion that the intensities of the same transitions observed in their ionization-detected OODR spectra are strongly affected by predissociation.

Double-resonance multiphoton ionisation studies of Franck-Condon disfavoured vibronic levels of the B̃ and C̃ Rydberg states of ammonia

Multiphoton optical-optical double-resonance spectroscopy via predissociating vibronic levels of the à state has been used to reveal hitherto uncharacterised vibrational modes of the B̃ and C̃′ Rydberg states of NH 3 and ND 3. The modes involved are ν 1 in the C̃′ state and ν 3 and ν 4 in the B̃ state; we present rotational analyses of ten bands involving these modes. We also describe a method for simulating the double-resonance spectra which takes account of the complications introduced by the short-lived nature of the intermediate state.

Optical-optical double-resonance spectroscopy of SrF: The F 2Σ +-B 2Σ + and G 2Π-B 2Σ + systems

Sub-Doppler optical-optical double-resonance spectra of SrF were recorded using two single-mode cw dye lasers. Via the intermediate state B 2Σ +, the F 2Σ + and G 2Π states were observed in the 32000 to 35000 cm −1 region above the ground state. The (1, 0), (2, 0), and (3, 0) bands of the F 2Σ +-B 2Σ + transition and the (0, 0) band of the G 2Π-B 2Σ + transition were rotationally analyzed. Rotational and vibrational constants for the F 2Σ + state and rotational constants for the G 2Π state are reported.

Optical-optical double-resonance spectroscopy of the 1 g( 3P 1) ion-pair state of Br 2

The 1 g ( 3P 1) ion-pair state of Br 2 has been observed for the first time by optical-optical double-resonance spectroscopy. The ion-pair state was excited from the X 1Σ g + ground state stepwisely through the A 3Π(1 u ) state: 1 g( 3 P 1)-A 3 Π(1 u)-X 1 Σ g + . The double-resonance transitions were then detected by the 265-nm emission which originated from the 1 g ( 3P 1) state radiating back to the A 3Π(1 u ) state. Energy level analysis of the 1 g ( 3P 1) state was made on the v = 0 to v = 9 levels of the 79Br 2 isotope species, giving the molecular parameters T e = 52 641.554(20), ω e = 153.8654(71), ω e χ e = 0.42863(69), B e = 0.042496(11), α e = 1.7005(84) × 10 −4, D e = 1.22(16) × 10 −8, and q = 1.13(23) × 10 −5 (all in cm −1 with 3σ in parentheses).