Rydberg states of the PO molecule

The absorption spectrum of the PO molecule in the region 2100 to 1550 Å has been studied in detail at high resolution. From a rotational analysis of the spectrum, a number of new electronic states have been discovered. Some of these electronic states have been assigned to Rydberg series of the various nl complexes of PO. An upper limit of the ground state dissociation energy has been lowered to 49090 cm^?1 (X²Π, T₀ = 0). Quantum defects are calculated and the first ionization potential of PO is improved to 67 532 cm^?1.     

Excited-state photoelectron spectra of the one-photon forbidden C3IIg rydberg state of molecular oxygen

The Rydberg C³II_g, state of molecular oxygen, which is one-photon forbidden from the ground electronic state, has been studied by means of (2 + 1) multiphoton ionization (MPI) ion-current and photoelectron spectroscopic techniques in the laser wavelength region 287–289 nm. Excitedstate photoelectron spectra have been observed at different rotational levels of the C³Π_gv' = 2 state of O₂, and show marked deviation from the Franck-Condon distribution generally expected in ionization of Rydberg electrons. Namely, in addition to main photoelectron peaks due to Δv = 0 transitions, other vibrational peaks are also observed with considerable intensities. The v⁺= 2 photoelectron peak shows different angular dependence from the other vibrational peaks. The rotational structure in the MPI ion-current spectrum of O₂ is well interpreted in terms of the rotational constants of the X²Π_g ground electronic state of O₂⁺.     

Analysis of autoionizing Rydberg states in the vacuum ultraviolet absorption spectrum of HBr and DBr

The photographic absorption spectrum of HBr and DBr above the first ionization limit (800–1000 Å) has been analyzed. No analyzable rotational structure was observed, indicating that the autoionization rate is faster than the rotational period. Two Rydberg series converging to the second ionization limit (²Σ⁺) have been identified, one with n^* = 2.75, 3.74, ,14.7, and the other with n^* = 2.35, 3.38. The symmetries cannot be determined conclusively, but the most probable assignment for the first series is 4pσ 4pπ⁴nsσ (¹Σ⁺) N = 6, 7, , 18, and for the second, 4pσ 4pπ·npσ and/or npπ[¹Σ⁺, ¹Π] N = 5, 6. Assuming that the intensity maxima assigned are band origins of vibronic states, a new ionization limit can be determined for HBr⁺(²Σ⁺): T₀ = 123 373 ± 20 cm⁻¹.     

Investigation of the 6p 2(3 P 0)n p Rydberg series of bismuth by multiphoton excitation

Rydberg states of the odd-parity series 6p ²(³ p ₀)n p of BiI are excited by a three-photon process. A two-photon dissociation of Bi₂ into excited atomic states followed by a one-photon absorption leads to highly excited atomic Rydberg states up ton = 32. States of the even-parity Rydberg series 6p ²(³ p ₀)nsJ=1/2,ndJ=3/2 andndJ=5/2 are also observed. In order to avoid the background caused by ionization of the bismuth molecules we performed a two-color excitation with pulsed dye lasers. With this experiment the 6p ²(³ p ₀)npJ=3/2 Rydberg series could be resolved up ton=75. The increasing quantum defect of this series is due to a perturbing state close to the first ionization limit. By a MQDT analysis we obtain the energy of the perturbing state and a value of 58,761.68±0.1 cm^?1 for the first ionization limit of atomic bismuth.     

Observation of autoionization resonances in uranium by step-wise laser photoionization

A large number of autoionization resonances have been observed in uranium in the energy range 50,590–51,560cm^–1 by two-step three-photon ionization technique, using two copper vapor laser pumped dye lasers. A Rydberg series converging to the ionization limit of UII at 1749cm^–1 (⁶ L _13/2) has been identified. Some of these resonances are very narrow with a fwhm of 0.1cm^–1. Possible origins of these are discussed.     

The electronic states of silicon monofluoride: Rydberg states

SCF-CI calculations are reported for the Rydberg states converging to the ground state of the SiF⁺ ion. The adjustment between the observed and calculated values for the energy of the first Rydberg B²Σ⁺ state has allowed the characterization of 15 observed ²Σ⁺ and ²Π Rydberg states. A value of 58960 cm^?1 has been obtained for the ionization potential of SiF. The A²Σ⁺ state appears to be a valence state with some Rydberg character.     

(2 + 1) Resonance enhanced multiphoton ionization of hydrogen chloride in a pulsed supersonic jet: Vacuum wavenumbers of rotational lines with detailed band analysis for excited electronic states of HCl

A comprehensive study of the excited electronic states of HCl is reported. Using resonance enhanced multiphoton ionization ((2 + 1) REMPI) and time-of-flight mass spectrometry (TOFMS) over 120 band systems are analyzed. Supersonic jet techniques are used to prepare rotationally cold species for laser spectroscopy in the 77 000 to 96 000 cm⁻¹ region. At least 50 new electronic states are characterized as well as several features only tentatively assigned previously. A long vibrational progression consisting of 29 vibrational levels of the deeply bound V¹Σ⁺(0⁺) valence/ion-pair state is studied. We also extend the identification and analysis to high vibrational levels of low-lying Rydberg states. The assignments of [²Π_i] Rydberg state complexes are evaluated in terms of spin-orbit coupling and united-atom calculations. In several band systems, the spectra exhibit anomalous rotational line intensities and broadened linewidths which are consistent with predissociation. Multiphoton ionization with mass spectrometry permits the investigation of isotope effects as well as the appearance of fragment species associated with repulsive potential curves.     

Low resolution VUV absorption spectrum of boron monoxide

The absorption spectrum of BO has been recorded between 2400 and 300 Å on the SA61 beam line of SUPERACO in Orsay. A new electronic transition has been observed and vibrationally analysed. Nine Rydberg states have been observed and classified into Rydberg series giving two ionization limits at 12.849eV for the X ¹Σ⁺ ionic state and at 13.117eV for the A ¹II state of BO⁺. Two ionization limits have been observed at 754 and 374 Å. The first of these corresponds to the B ¹Σ⁺ state and the last one to the C ¹Σ⁺ state of BO⁺. The new results are compared with the ab initio calculations of Karna and Grein concerning BO and BO⁺. The agreement is satisfactory.     

Three photon resonant ionization in atomic potassium via S,P, D and F series Rydberg states

Single colour three photon resonant ionization (2 + 1) is observed in atomic potassium vapour in a heat pipe oven using an excimer laser pumped dye laser. Using wavelengths between 570 nm and 603 nm various²S and²D Rydberg states are populated by two photon excitation. Third photon of the same wavelength ionizes the atoms. Rydberg states up ton ⋍ 50 are observed. Electric field as low as 1 V/cm causes extensive Stark mixing of the states. This results in progressively higher three photon ionization signals via the perturbed²P and²F Rydberg states. The three photon ionization process is studied using both linearly and circularly polarized incident light. The experiment shows qualitatively that the²P Rydberg states are perturbed primarily by the²D states in the prescence of an external electric field and to a much smaller extent by²S states. This is also explained theoretically by calculating the Stark mixing coefficients under the Bates and Daamgard (1949) approximation. Implication for a similar effect in other alkali elements is discussed.     

Ru原子高Rydberg态研究

本文描述用激光共振激发-场电离实验方法测定Ru原子的4d⁷(⁴F)ns(n=28—45)和4d⁷(⁴F)nd(n=26—48)系列Rydberg能级,并应用非线性拟合得到了Ru原子的第一电离阈值。采用相对论性自洽场方法对所得能级以及相应的量子亏损作了计算,理论与实验结果符合得很好。此外还将本文所得的第一电离阈值与已有数据作了比较。 关键词：     

NO2分子的光学-光学双色双共振多光子离化谱

以Nd:YAG激光器的二倍频输出光为抽运光,其三倍频输出抽运的光学参量发生/放大器输出光为探测光,利用光学-光学双色双共振多光子离化光谱技术(OODR-MPI),获得了NO₂分子在605—675nm探测光波长范围内的多光子离化激发谱. 通过对NO₂分子离化机理的分析,确定了在此波长区间,NO₂分子经1+3+1双共振多光子过程离化,离化通道为NO₂(X²A₁)hν 关键词： 2')" href="#">NO₂ 光学-光学双共振多光子离化谱 里德伯态 分子常数     

Oscillator strength measurements of the 3p ↦ nd Rydberg transitions of sodium

We report new measurements of the oscillator strengths of the 3p ²P_3/2 ↦nd ²D_{5/2, 3/2} and 3p ²P_1/2 ↦ nd ²D_3/2 Rydberg transitions of sodium using a thermionic diode ion detector in conjunction with the Nd:YAG pumped dye lasers. The ns ²S_1/2 and nd ²D_5/2,3/2 Rydberg series have been recorded via two-step excitation, from the 3p ²P_3/2 and 3p ²P_1/2 intermediate states. Employing the saturation technique, the photoionization cross sections from the 3p ²P_3/2 and 3p ²P_1/2 intermediate states at the first ionization threshold are determined as 7.9(1.3) Mb and 6.7(1.1) Mb respectively. The f-values of the Rydberg transitions are calibrated with the photoionization cross section measured at the first ionization threshold and compared with the earlier data.     

Rydberg transitions of aniline and N,N-diethylaniline

The absorption spectra of aniline and N,N-diethylaniline in the gaseous and condensed phases were measured in the 30 000–60 000 cm^?1 region. The magnetic circular dichroism (MCD) spectra of these compounds in the gas phase and in solution were also measured in the region 30 000–49 000 cm^?1. The MCD signals due to the Rydberg transitions were newly observed for N,N-diethylaniline. On the basis of these data, we demonstrated that in the region below 50 000 cm^?1 the Rydberg transition bands appear at 47 180 cm^?1 for aniline and at 36 520, 38 880, and 42 000 cm^?1 for N,N-diethylaniline. Besides these, in the region higher than 50 000 cm^?1, a number of Rydberg transition bands were observed for both compounds in the gaseous state. The observed Rydberg transition bands were analyzed with the aid of the Rydberg formula: they were assigned for aniline to the np- and nd-type series converging to the first and second ionization potentials, and for N,N-diethylaniline to the us- and two np-type series converging to the first ionization potential.     

The spectrum of Si18O in the vacuum ultraviolet region

The absorption spectrum of Si¹⁸O has been photographed at high resolution in the region 1200–1500 Å. Nine of the recently reported eleven excited states found in this region from a study of Si¹⁶O have been verified and their v numbering settled. From the Rydberg states a value of the ionization potential has been derived.     

Higher electronic states of ReF6

The ultraviolet absorption of ReF₆ comprises a broad (δ⁻ = 3760 cm⁻¹) structureless band centered at 47 687 cm⁻¹ and two structured systems originating at 49 322 and 56 404 cm⁻¹. The first is interpreted as a charge transfer transition. The other two are interpreted as members of a Rydberg series converging on an ionization potential of 7.99 eV. The molecule, in the Rydberg states, is a slightly expanded octahedron     

Autoionization in the evolution process of dense Rb Rydberg atoms in nP states

The autoionization mechanisms of dense nP_3/2 (n = 20–97) Rydberg gases of ⁸⁷Rb atoms in the spontaneous evolution were investigated for the first time. By observing the characteristic time of the electrons generated through autoionization process, the dependence of autoionization mechanisms (black-body radiation, electron–Rydberg collision, and Penning ionization) on the principal quantum number n of initial nP states was demonstrated. The dependence on the number n in nP Rydberg atoms is similar to those in nD Rydberg atoms.     

STUDY OF HIGH-LYING EXCITED STATES OF RARE-EARTH ELEMENT Dy BY LASER RESONANCE IONIZATION SPECTROSCOPY

This paper describes the investigation of high-excited states of Dy. which includes the measurement of high Rydberg states and autoionizing states, by means of laser resonance ionization spectroscopy (LRIS). Two high Rydberg series (n>40), 4f¹⁰(⁵I₈) 6sns and 4f¹⁰(⁵I₈) 6snd, have been obtained by exciting the state of 4f¹⁰(⁵I₈) 6s6p (³P⁰₂) ⁵I⁰₈ using two-step laser excitation-electric field ionization method. With the data obtained, we determined the first ionization potential of Dy. It is 47901.7±0.6 cm^-1, that is. about one order more accurate than the results given in the literature. Using the same technique, we found 97 autoionizing states by exciting the state of 4f⁹5d6s(⁷H⁰₇).     

SF自由基的REMPI光谱：观测到一个新的2§电子态

利用SF6/Ar混合气沿气束方向放电， 产生SF自由基．在306?321 nm范围内扫描激光波长得到SF自由基(2+1) REMPI光谱． 观测到2§?X2|双光子跃迁的５ 个振转谱带， 通过对实验谱分析获得新观测到2§里德堡态的转动常数近似值和振动频率约815 cm?1；同时对2|3=2?X2|3=2跃迁谱带进行了转动分析，转动常数B0v?0.42 cm?1，该谱带对应着(1+2) REMPI机理；对SF自由基电离解离机理也进行了讨论．