Electronic States Of NO Research Articles

Dissociation of High-Lying Electronic States of NO2+ in the 15.5-20 eV Region.

We present a dissociative photoionization study of NO2 in the 15.5-20 eV energy range using synchrotron radiation-based double imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy. The high-lying electronic states of the NO2+ cation, c 3B1, C 1B1, d 3A1, e 3B2, and D 1B2, are prepared in well-resolved vibronic states in order to study their individual dissociation mechanisms. Up to eight dissociation limits of NO2+ are reached, and mass-selected threshold photoelectron spectra (TPES) show that the c 3B1, C 1B1, and d 3A1 states predominantly dissociate into the NO+ + O products, while the e 3B2 and D 1B2 states can undergo fragmentation into both the NO+ + O and the O+ + NO channels, as well as the O2+ + N channel with a small yield. Overall, these product yields are found to be quite sensitive to autoionization processes. Mass-selected high-resolution electron and ion kinetic energy correlation diagrams reveal dissociative mechanisms that possess strong state-specific character.

Coherent interference of molecular electronic states in NO by two-color femtosecond laser pulses

Quantum coherence interference between electronic states in molecules is an important factor for controlling electronic and nuclear dynamics in photoinduced physics and chemistry. We measure and model molecular angle-dependent photoionization yields to explore coherent interference dynamics between quasiequal energy electronic-vibrational states of the nitric oxide molecule, NO, by ultrafast phase-controlled two-color femtosecond laser pulses. We demonstrate by experiment and theory that the photoelectron angular distribution of NO, where two excited electronic states are coherently combined by ultrafast pulses, is a function of the relative phase of the pulses, and the photoelectron kinetic energy. The modification of photoelectron emission angular patterns encodes the information of the coherence via electronic state interference. The result allows access to phase-dependent state correlations and ultrafast vibrationic dynamics in molecules.

An FTIR emission study of the products of NO A2Σ+ (v = 0, 1) + O2 collisions.

Collisional quenching of NO A2Σ+ (v = 0, 1) by O2 has been studied through the detection of vibrationally excited products by time-resolved Fourier transform infrared emission spectroscopy. Non-reactive quenching of NO A2Σ+ (v = 0) produces a vibrational distribution in NO X2Π which has been quantified for v = 2-22, and is found to be bimodal. The results are consistent with two quenching channels. The first forms the ground X3Σ or low-lying a 1Δg electronic state of O2 with a distribution including high vibrational levels of NO X2Π which is slightly hotter than statistical. Two possibilities are identified for the second channel. The first, with a similar quantum yield to that producing higher vibrational levels, forms a highly electronically excited state, such as O2 c1Σ, with low vibrational levels in NO X2Π which are inverted with a distribution resembling that resulting from a sudden or harpoon mechanism. The second is that ground state oxygen is formed with low vibrational energy partitioned into NO X2Π. In addition, vibrationally excited NO2 is observed, but at intensities which indicate that it is formed in low quantum yield. Quantitatively unobservable processes (defined as those which do not form ground state NO (v ≥ 2)) are found to have a branching ratio of at most 25 ± 5%. The results are compared with those of previous studies and the most consistent interpretation suggests that dissociation of O2 to form ground state O(3P) atoms and ground vibrational state NO X2Π (v = 0) is the main reactive process rather than NO2 formation. Qualitatively similar results are seen for the quenching of NO A2Σ+ (v = 1).

Electronic structure, stability and spectroscopy of low-lying states of NO−, HNO− and HON− molecular anions

Accurate post Hartree-Fock methods have been used to investigate electronic structure, spectroscopy, stability and metastability of low-lying electronic states of HNO, HON, NO, NO−, HNO− and HON−. Accurate vertical transition energies between lowest electronic states of HNO and HON isomers have been determined. The HNO vertical transition energy of the X∼1A′-ã3A″ transition is shown to be 0.87eV. Core-valence correlations and relativistic corrections have been taken into account to determine accurately spectroscopic constants of electronic states of NO− and NO. Adiabatic excitation energies and dipole moments of low-lying electronic states of NO− have also been calculated. The adiabatic electron affinity of NO has been deduced to be 0.0289eV, which is in excellent agreement with the experimental value of 0.026±0.05eV. The comparison of potential energy curves of low-lying states of NO/NO−, HNO/HNO− and HON/HON− reveals short-lived excited electronic states. The HON− anion appears as an unbound anion unlike to HNO− which is a bound anion. Three-dimensional potential energy surfaces (3D-PESs) for both HNO (X∼1A′) and HNO−(X2A″) ground states, have been generated and fitted by second order perturbation theory to produce accurate spectroscopic constants. Spectroscopic data of HNO−(X2A″) deduced from this work is computed for the first time.

Spectroscopic study of some diatomic molecules via the proper quantization rule

Spectroscopic techniques are very essential tools in studying electronic structures, spectroscopic constants and energetic properties of diatomic molecules. These techniques are also required for parametrization of new method based on theoretical analysis and computational calculations. In this research, we apply the proper quantization rule in spectroscopic study of some diatomic molecules by solving the Schr\"odinger equation with two solvable quantum molecular systems-Tietz-Wei and shifted Deng-Fan potential models for their approximate nonrelativistic energy states via an appropriate approximation to the centrifugal term. We show that the energy levels can be determined from its ground state energy. The beauty and simplicity of the method applied in this study is that, it can be applied to any exactly as well as approximately solvable models. The validity and accuracy of the method is tested with previous techniques via numerical computation for H$_2$ and CO diatomic molecules. The result also include energy spectrum of 5 different electronic states of NO and 2 different electronic state of ICl.

Conical intersections between [formula omitted] and [formula omitted] electronic states of [formula omitted

We explore both the general symmetry-allowed accidental (SAA) conical intersections (CIs) and Renner–Teller (RT) interactions prevailed between the ground (X2A1) and first excited (A2B2) electronic states of NO2 in the configuration space of normal mode coordinates. Global ab initio potential-energy surfaces and Non Adiabatic Coupling Term (NACT) between those states are reported. For each of the three pairs of normal mode (Q1,Q2,Q3), calculated NACT show singularity at different positions, which are used to calculate Adiabatic-to-Diabatic Transformation (ADT) angles and thereby, the diagonal elements of ADT matrix display (i) sign change for odd number of SAA CI (s) and (ii) no sign change for even number of SAA CIs as well as Renner–Teller interactions. Similar to Jahn–Teller CI, the existence of SAA CIs are, further, confirmed by Longuet-Higgins’ phase change.

Low-lying Adiabatic Electronic States of NO: a QMC Study

Low-lying Adiabatic Electronic States of NO: a QMC Study

Ab Initio-Based Global Double Many-Body Expansion Potential Energy Surface for the First 2A″ Electronic State of NO2

An ab initio-based global double many-body expansion potential energy surface is reported for the first electronic state of the NO(2)((2)A") manifold. Up to 1700 ab initio energies have been employed to map the full configuration space of the title molecule, including stationary points and asymptotic channels. The calculated grid energies have been scaled to account for the incompleteness of the basis set and truncation of the MRCI expansion and fitted analytically with a total root-mean-squared-deviation smaller than 1.0 kcal mol(-1). The lowest point of the potential energy surface corresponds to the (2)B(1) linear minimum, which is separated from the C(s) distorted minimum by a C(2v) barrier of ≈9.7 kcal mol(-1). As usual, the proposed form includes a realistic representation of long-range interactions. Preliminary work indicates its reliability for reaction dynamics.

Electronic-resonance-enhanced coherent anti-Stokes Raman scattering of nitric oxide: Saturation and Stark effects

A theoretical analysis of electronic-resonance-enhanced (ERE) coherent anti-Stokes Raman scattering (CARS) of NO is described. The time-dependent density-matrix equations for the nonlinear ERE-CARS process are derived and manipulated into a form suitable for direct numerical integration. In the ERE-CARS configuration considered in this paper, the pump and Stokes beams are far from electronic-resonance. The visible 532 and 591 nm laser beams are used to excite Q-branch Raman resonances in the vibrational bands of the X (2)Pi electronic state of NO. An ultraviolet probe beam at 236 nm is used to excite P-, Q-, or R-branch transitions in the (v'=0, v"=1) band of the A (2)Sigma(+)-X (2)Pi electronic system of NO molecule. Experimental spectra are obtained either by scanning the ultraviolet probe beam while keeping the Stokes frequency fixed (probe scans) or by scanning the Stokes frequency while keeping the probe frequency fixed (Stokes scans). The calculated NO ERE-CARS spectra are compared with experimental spectra, and good agreement is observed between theory and experiment in terms of spectral peak locations and relative intensities. The effects of saturation of the two-photon Raman-resonant Q-branch transitions, the saturation of a one-photon electronic-resonant P-, Q-, or R-branch transitions in the A (2)Sigma(+)-X (2)Pi electronic system, and the coupling of these saturation processes are investigated. The coupling of the saturation processes for the probe and Raman transitions is complex and exhibits behavior similar to that observed in the electromagnetic induced transparency process. The probe scan spectra are significantly affected by Stark broadening due to the interaction of the pump and Stokes radiation with single-photon resonances between the upper vibration-rotation probe level in the A (2)Sigma(+) electronic levels and vibration-rotation levels in higher lying electronic levels. The ERE-CARS signal intensity is found to be much less sensitive to variations in the collisional dephasing rates under saturation conditions.

Photolysis of tert-Butylthionitrite via Excitation to the S1 and S2 States Studied by 3d-REMPI Spectroscopy

S-Nitrosothiols serve as carriers and donors of NO in several important biological signaling systems. In these compounds the S-NO bond is rather labile and NO can be released thermally or photochemically. This paper reports on the photolytical decomposition of tert-butylthionitrite (t-BuSNO) in the visible and near-UV spectral regions. Between 500 and 605 nm several vibronic levels of the S(1) (npi*) state were excited, including the electronic origin. At 360 nm t-BuSNO is excited near the maximum of the first UV band assigned to the S(2) (pipi*) state. The velocity distributions of several hundred rovibrational states of the NO fragments were recorded with the recently developed 3d-REMPI method. A global fit to these data yields populations of the rovibrational states in both spin-orbit components of the (2)Pi electronic state of NO as well as their velocity distributions and angular anisotropies beta. These data also carry the distribution functions for internal and kinetic energy of the counterfragment, the t-BuS radical. The range found for the anisotropy parameter confirms the npi* character of the visible absorption band (-1.0 < beta < -0.8), and the pipi* character of the UV band (beta = 1.2). Mode-specific dissociation has been observed for excitation into several vibronic bands of the S(0) → S(1) transition. Some produce NO exclusively in the ν = 0 vibrational ground state, whereas some others produce NO almost entirely in the ν = 1 vibrationally excited state. It is concluded that photodissociation is faster than relaxation of the NO stretch vibration of t-BuSNO in S(1) and that it proceeds on purely repulse potential energy surfaces in both electronic states.

A brief introduction and some background to the article JQSRT 1998;60:1025–31 and its companion

This note provides a short introduction, some background information and relevant history related to reprint of the article “Atmospheric remote-sensing reference data from GOME: Part 1. Temperature-dependent absorption cross-sections of NO 2 in the 231–794 nm range” (JQSRT 1998;60:1025–31). The article and its companion “Atmospheric remote-sensing reference data from GOME: 2. Temperature-dependent absorption cross sections of O 3 in the 231–794 nm range” (JQSRT 1999;61:509–17) provided timely and unique data sets of the absorption cross sections of Nitrogen dioxide, NO 2, and ozone, O 3. The reported absorption cross sections have a spectral resolution sufficient to distinguish the electronic vibrational and rotational features of NO 2 and O 3 and were made in the temperature range of relevance to the earth's atmosphere, viz. 200–300 K, over a wide spectral range. These species are two of the most important trace gases in earth's atmosphere, and play key roles in determining the chemistry and dynamics of the earth's atmosphere and the conditions at the earth's surface experienced by the biosphere. Whilst providing valuable information about the electronic states of NO 2 and O 3, these spectra were determined primarily for their exploitation in the retrieval of trace gases from measurements of solar back scattered radiation by ground based and space borne instrumentation. These yield the local and global amounts and distributions of NO 2 and O 3, thereby constraining our knowledge about atmospheric chemistry and dynamics and the impact of pollution from the local to the global scale. The measurement, publication and use of these spectral sets are among many important milestones in the development of atmospheric remote sensing.

Quantum Interference in NO2

This paper investigates the origin of a quantum interference observed when NO(2) is dissociatively ionized by short pulses of ultraviolet light. We describe time-resolved measurements of NO(+), O(+), and NO(2)(+) ions produced following the interaction of NO(2) with a approximately 70 fs duration pulse centered close to 400 nm and a subsequent time-delayed probe pulse close to 269, 205, or 400 nm. A quantum beat oscillation with a period of 524 fs and a characteristic damping time of 8 ps is observed on all transient ion signals. We investigate the effect of tuning the central wavelength of the excitation pulse over a 12 nm range, and we discuss the potential importance of three possible multiphoton pathways involving one, two, and three pump photons. We conclude that the ionization pathway responsible for the beat signal is most likely due to a process involving the absorption of two pump photons and two probe photons. This presents an interesting problem with respect to the interpretation of the mechanism responsible for the quantum interference signature since the electronic states of NO(2) reached at the two-photon level are all thought to be extremely short-lived and to dissociate on a time scale that is far shorter than the characteristic damping time of the oscillatory signals. We suggest that a possible explanation for the observed dynamics is associated with a minor dissociation channel of the (2)(2)B(2) state of NO(2) through its interaction with the longer lived (2)(2)A(1) state.

Theoretical study of the influence of laser intensity on the population of the NO molecule electronic states

Using the time-dependent wavepacket method and employing the four-state model，the influence of the laser intensity on the population of the NO molecule electronic states are calculated in this paper. The populations of the electronic states of the NO are given by the wavefunctions obtained by solving the Schrdinger equation through the split-operator Fourier transform method. The calculated results show that different pump pulse intensities have different influences on the population of the electronic states of NO. By changing the pulse intensity，the ionization ratio can be controlled，which will benefit the light manipulation of atomic and molecular processes.

MRCISD and GVVPT3 study of the low-lying electronic states of NO−

The ground electronic state (X 3Σ−) and three low-lying excited electronic states, 11Σ+, 11Δ, and 13Π, of NO− were studied using MRCISD and GVVPT3 with the aug-cc-pVXZ (X = D, T, Q) basis sets and extrapolated to complete basis set limits. The thermodynamic constants, re , ωe , ωexe , and De , are predicted to be in good agreement with experimental values, where available. The increase of basis set lowers substantially the potential well of 13Π with respect to the ground state, e.g. the value of Te , 18425 cm−1 by MRCISD/aug-cc-pVDZ, decreases to 10829 cm−1 by MRCISD at the complete basis set limit. Additional calculations, using perturbative corrections for triple and quadruple excitations to MRCISD, i.e. MRCISD(TQ), showed that inclusion of triples and quadruples are essential to predictions of the electron affinity of NO, resulting in an increase in electron binding of over 0.36 eV.

Computed lifetimes of metastable states of the NO2+ dication

Based on the ab initio potential energy, spin-orbit coupling, electronic transition dipole moment, and radial nonadiabatic coupling functions, the energy level positions, lifetimes, and radiative transition probabilities (Einstein A coefficients) have been determined for the lowest electronic states of NO2+ using the log-amplitude-phase, stabilization, and complex-scaling methods. The calculated characteristics are in reasonable agreement to the available experimental data, thus, evidencing the reliability of the theoretical predictions for the characteristics unobserved to date. With the exception of the v<or=2 vibrational states of the B 2Sigma+ electronic state, the calculated radiative lifetimes of the excited electronic states are longer than their predissociation lifetimes, hence, accounting for the failure of the attempts which have been made so far to observe any emission from the latter states.

Excitation of the A 2Σ +, C 2Π and D 2Σ + Rydberg-electronic states in NO by 100 eV electrons

We report differential cross sections and optical oscillator strength determinations for the respective excitation of vibrational sub-levels of the A 2Σ +, C 2Π and D 2Σ + electronic states in NO by 100 eV electrons. While the differential cross section measurements are original, the present optical oscillator strengths are compared where possible with earlier values. In particular, a detailed comparison is made with the dipole (e,e) spectroscopy data from Chan et al. [W.F. Chan, G. Cooper, C.E. Brion, Chem. Phys. 170 (1993) 111], with generally very good agreement being found.

Comment on ‘Electron scattering and ionization of NO, N2O, NO2, NO3 and N2O5 molecules: theoretical cross sections’

In their recent paper, Joshipura et al (2007 J. Phys. B: At. Mol. Opt. Phys. 40 199–210) inadvertently neglected to compare the results of their calculation of integral cross sections for excitation of the sum of all the electronic states in NO to existing experimental data (Brunger et al 2000 J. Phys. B: At. Mol. Opt. Phys. 33 809–19). In this comment such a comparison is now made, with the level of agreement between them found to be marginal.

Effects of multimode Jahn-Teller coupling on the photodetachment spectrum of nitrate anion ( [formula omitted

The multimode static and dynamic Jahn-Teller effects in the 2E″ and 2E′ excited states of the nitrate radical (NO 3) and their impact on the vibronic structure of the photodetachment spectrum of the nitrate anion are investigated theoretically. The analysis rests on the quadratic vibronic coupling approach and large-scale multi-reference configuration interaction calculations for the determination of the respective coupling parameters. The possible pseudo-Jahn-Teller interactions between the ground 2 A 2 ′ and excited 2E′ electronic states of NO 3 are also included in the vibronic coupling model. The results of the 2E″ state are compared with the experimental recording of Neumark and co-workers, while those for the 2E′ state come as a prediction. The deviations between theoretical and experimental vibronic structures of the 2E″ photoelectron band are discussed.

Effect of CO2 on Nonthermal-Plasma Reactions of Nitrogen Oxides in N2. 1. PPM-Level Concentrations

PPM-level concentrations of CO2 are added to NO/N2 mixtures to determine the effect of CO2 on plasma generation and to investigate the mechanism of CO2 reactions. Addition of 599.9 ppm CO2 does not affect the electric discharge in NOx in N2 nonthermal plasma. However, CO2 slightly dissociates, with CO2 conversion reaching a maximum of about 5.5% at the power input at which NO conversion ceases. NO(A), the first-excited electronic state of NO, is detected by corona-induced optical emission and is found to contribute to CO2 dissociation. A kinetic model including 38 reactions is required to adequately model decomposition of NOx and CO2 in the presence of CO2. About 18% of the NO(A) that is formed reacts with CO2 to form NO, CO, and O.

State-Selective Production of Vibrationally Excited NO2+ by Double-Resonant Photoionization

Two-color, two-photon resonant, three-photon ionization, and high-resolution photoelectron spectroscopy are combined to characterize the photoionization dynamics of the 3pσ 2 electronic state of NO2. Direct photoionization of selected vibrational levels of the NO2 3pσ 2 state shows a strong propensity to preserve the vibrational quantum numbers of the intermediate state. Efficient methods for producing NO2+ X 1 (000), (010), (100), and (001) with over 95% purity are discussed. This approach is expected to be applicable to the study of the mode dependence of the effects of vibrational excitation in ion−molecule reactions involving NO2+.