Tunable Vacuum Ultraviolet Laser Research Articles

Infrared + vacuum ultraviolet two-color ionization spectroscopy of neutral metal complexes based on a tunable vacuum ultraviolet free-electron laser.

This paper describes an experimental technique for studying neutral metal complexes using infrared + vacuum ultraviolet (IR+VUV) two-color ionization spectroscopy based on a tunable VUV free-electron laser (VUV-FEL). The preliminary IR spectroscopy results of mass-selected nickel tetracarbonyl are reported in this work. The results demonstrate that the tunable VUV-FEL light allows the selective ionization of a given neutral cluster free of confinement along with the recording of well-resolved IR spectra. As the ionization energies of many neutral clusters are accessible by a broadly tunable VUV-FEL (50-150 nm) and near-threshold ionization can be readily achieved, the proposed experimental method offers unique possibilities for the size-specific study of a wide variety of confinement-free neutral clusters.

Photodissociation branching ratios of 12C16O from 108000 cm−1 to 113200 cm-1 measured by two-color VUV-VUV laser pump-probe time-slice velocity-map ion imaging method: Observation of channels for producing O(1D)

The photoabsorption and photodissociation of carbon monoxide (CO) in the vacuum ultraviolet (VUV) region is one of the most important photochemical processes in the interstellar medium, thus it has attracted numerous experimental and theoretical studies. Here, we employed the two-color VUV-VUV laser pump-probe time-slice velocity-map ion imaging method to measure the relative branching ratios [C(3P0)+O(1D)]/ {[C(3P0)+O(3P)]+ [C(3P0)+O(1D)]} and [C(3P2)+O(1D)]/ {[C(3P2)+O(3P)]+[C(3P2)+O(1D)]} in the VUV photoexcitation energy range of 108000−113200 cm−1. Here, one tunable VUV laser beam is used to excite CO to specific rovibronic states, and a second independently tunable VUV laser beam is used to state-selectively ionize C(3P0) and C(3P2) for detection. State-selective photoionization through the 1VUV+1UV/visible resonance-enhanced multiphoton ionization scheme has greatly enhanced the detection sensitivity, which makes many new weak absorption bands observable in the current study. The branching ratio measurement shows that the spin-forbidden channels C(3P0)+O(1D) and C(3P2)+O(1D) only open at several discrete narrow energy windows. This might be caused by certain accidental resonance-enhanced spin-orbit interactions between the directly excited Rydberg states and valence states of triplet type which finally dissociate into the spin-forbidden channels.

Infrared Spectroscopy of Neutral Water Dimer Based on a Tunable Vacuum Ultraviolet Free Electron Laser

Infrared (IR) spectroscopy provides detailed structural and dynamical information on clusters at the fingerprint level. Herein, we demonstrate the capability of a tunable vacuum ultraviolet free electron laser (VUV-FEL) for selective detection of a wide variety of neutral water clusters and for recording the size-dependent IR spectra. The present technique does not require the presence of an ultraviolet chromophore or a dipole moment and is generally applicable for IR spectroscopy of neutral clusters free from confinement. To show the features of our technique, we report here the IR spectra of neutral water dimer in the OH stretch region, providing benchmarks for theoretical study of the accurate description of hydrogen bonding structures involved in liquid water and ice. Quantum mechanical calculations on a 12-dimensional ab initio potential energy surface are utilized to simulate the anharmonic vibrational spectra of water dimer. These results help to resolve the controversy of the exact vibrational assignment of each band feature of the water dimer.

Observation of the Carbon Elimination Channel in Vacuum Ultraviolet Photodissociation of OCS.

The textbook mechanism for OCS photodissociation mainly involves the CO + S or CS + O product channel via a single bond fission. However, a third dissociation channel concerning the cleavage of both C-S and C-O bonds yielding SO + C products, though thermodynamically allowed, has never been verified experimentally to date. By using a tunable vacuum ultraviolet laser light and time-sliced velocity map ion imaging technique, we have clearly observed the SO(X3Σ-) + C(3PJ=0) products as the vacuum ultraviolet laser photon energy gradually exceeds its thermodynamic threshold. The corresponding SO(X3Σ-) coproducts are highly vibrationally excited and show varying angular distributions from isotropic to anisotropic as the excitation photon energy increases. Theoretical analysis suggests that a fast nonadiabatic pathway plays a dominant role in the formation of the anisotropic SO products. That isotropic products arise as the excitation photon energies approach the thermodynamic threshold can be reasonably explained by the "roaming mechanism".

Rotational dependence of the branching ratios and fragment angular distributions for the photodissociation of 12C16O in the Rydberg 4p(2) and 5p(0) complex region (92.84-93.37 nm).

12C16O shows complicated absorption structures in the wavelength range of 92.84-93.37 nm caused by the mutual interactions among the Rydberg 4p(2) and 5p(0) complexes, and several diffuse valence states. Here, we systematically measured the branching ratios and fragment angular distributions for the photodissociation of 12C16O in the wavelength range using our mini-time-slice velocity-map imaging (mini-TSVMI) setup and a tunable vacuum ultraviolet (VUV) laser radiation source generated by the two-photon resonance-enhanced four-wave mixing scheme. Various patterns of rotational dependence for the photodissociation branching ratios have been observed for different vibronic states, and they are found to be consistent with previous spectroscopic investigations, revealing the complicated coupling schemes and predissociation dynamics in this region. Irregular angular distributions of the photofragments have been observed, especially in the Rydberg 5p(0) complex region. This has been attributed to the simultaneous excitation of multiple states with different symmetries in this region. The newly observed underlying continuum in the Rydberg 5p(0) complex region has been directly detected in the present study, and it is found to be of 1Σ+ symmetry and dissociates predominantly into the C(3P) + O(3P) channel. This study generally confirms the results of previous spectroscopic studies from a different perspective, and adds new knowledge for understanding the complicated predissociation dynamics of 12C16O in the titled wavelength range.

Photodissociation dynamics of H2O at 111.5 nm by a vacuum ultraviolet free electron laser.

Photodissociation dynamics of H2O via the F̃ state at 111.5 nm were investigated using the high resolution H-atom Rydberg "tagging" time-of-flight (TOF) technique, in combination with the tunable vacuum ultraviolet free electron laser at the Dalian Coherent Light Source. The product translational energy distributions and angular distributions in both parallel and perpendicular directions were derived from the recorded TOF spectra. Based on these distributions, the quantum state distributions and angular anisotropy parameters of OH (X) and OH (A) products have been determined. For the OH (A) + H channel, highly rotationally excited OH (A) products have been observed. These products are ascribed to a fast direct dissociation on the B̃1A1 state surface after multi-step internal conversions from the initial excited F̃ state to the B̃ state. While for the OH (X) + H channel, very highly rotationally excited OH (X) products with moderate vibrational excitation are revealed and attributed to the dissociation via a nonadiabatic pathway through the well-known two conical intersections between the B̃-state and the X̃-state surfaces.

Photodissociation Dynamics of Diacetylene Rydberg States

The state-selective photodissociation of diacetylene (C4H2) was studied in the wavelength range of 127.5-164.4 nm by high-resolution Rydberg H atom time-of-flight spectroscopy measurements. In the wavelength region, two Rydberg series nR and nR' were state-selectively excited using tunable vacuum-ultraviolet laser radiation. In all photolysis wavelengths, two decay channels with different dissociation dynamics were observed. In one channel, the characteristic and isotropic translational energy distributions with a peak around 1800 cm(-1) can be found, suggesting statistical dissociation through internal conversion (IC) from the Rydberg state to the ground state and then dissociation on the ground-state surface. In contrast to this, in the second channel, nonstatistical and anisotropic translational energy distributions were observed, possibly through IC to the excited repulsive state. The vibrational progressions of C4H (A(2)Π) products have also been observed and assigned to the CCC bend and C≡C stretch progressions in the second channel at 3R Rydberg states.

VACUUM ULTRAVIOLET LASER PHOTOION AND PULSED FIELD IONIZATION–PHOTOION STUDY OF RYDBERG SERIES OF CHLORINE ATOMS PREPARED IN THE ${}^{2}{{\rm{P}}}_{J}$ (J= 3/2 and 1/2) FINE-STRUCTURE STATES

We have measured the high-resolution vacuum ultraviolet (VUV) photoion (VUV-PI) and VUV pulsed-field ionization–photoion (VUV-PFI-PI) spectra of chlorine atoms (Cl) in the VUV energy range 103,580–105,600 cm−1 (12.842–13.093 eV) using a tunable VUV laser as the photoexcitation and photoionization source. Here, Cl atoms are prepared in the Cl(2P3/2) and Cl(2P1/2) fine-structure states by 193.3 nm laser photodissociation of chlorobenzene. The employment of VUV-PFI-PI detection has allowed the identification of Rydberg transitions that are not observed in VUV-PI measurements. More than 180 new Rydberg transition lines with principal quantum number up to n = 61 have been identified and assigned to members of nine Rydberg series originating from the neutral Cl(2P3/2) and Cl(2P1/2) fine-structure states. Two of these Rydberg series are found to converge to the Cl+(3P2), four to the Cl+(3P1), and three to the Cl+(3P0) ionization limits. Based on the convergence limits determined by least-squares fits of the observed Rydberg transitions to the modified Ritz formula, we have obtained a more precise ionization energy (IE) for the formation of the ionic Cl+(3P2) from the ground Cl(2P3/2) state to be 104,591.01 ± 0.13 cm−1. This is consistent with previous IE measurements, but has a smaller uncertainty. The analysis of the quantum defects obtained for the Rydberg transitions reveals that many high-n Rydberg transitions are perturbed.

Tunable vacuum ultraviolet laser based spectrometer for angle resolved photoemission spectroscopy

We have developed an angle-resolved photoemission spectrometer with tunable vacuum ultraviolet laser as a photon source. The photon source is based on the fourth harmonic generation of a near IR beam from a Ti:sapphire laser pumped by a CW green laser and tunable between 5.3 eV and 7 eV. The most important part of the set-up is a compact, vacuum enclosed fourth harmonic generator based on potassium beryllium fluoroborate crystals, grown hydrothermally in the US. This source can deliver a photon flux of over 10(14) photon/s. We demonstrate that this energy range is sufficient to measure the k(z) dispersion in an iron arsenic high temperature superconductor, which was previously only possible at synchrotron facilities.

High power all solid state VUV lasers

We report the investigation on the high power all solid state vacuum ultra-violet (VUV) lasers by means of nonlinear frequency conversion with KBe2BO3F2 (KBBF) nonlinear crystal. Several all solid state VUV lasers have developed in our group, including polarization and pulse repetition rate adjustable picosecond 177.3nm VUV laser, wavelength tunable nanosecond, picosecond and femtosecond VUV lasers, high power ns 177.3nm laser with narrow linewidth. The VUV lasers have impact, accurate and precise advantage.

Communication: State-to-state photodissociation study by the two-color VUV-VUV laser pump-probe time-slice velocity-map-imaging-photoion method

We demonstrate that combining two independently tunable vacuum ultraviolet (VUV) lasers and the time-slice velocity-map-imaging-photoion (VMI-PI) method allows the rovibronically state-selected photodissociation study of CO in the VUV region along with the state-selective detection of product C((3)P(0,1,2)) using the VUV-UV (1+1') resonance-enhanced photoionization and the VUV Rydberg autoionization methods. Both tunable VUV lasers are generated based on the two-photon resonance-enhanced four-wave mixing scheme using a pulsed rare gas jet as the nonlinear medium. The observed fine-structure distributions of product C((3)P(J)), J = 0, 1, and 2, are found to depend on the CO rovibronic state populated by VUV photoexcitation. The branching ratios for C((3)P0) + O((3)P(J)): C((3)P0) + O((1)D2), C((3)P1) + O((3)P(J)): C((3)P1) + O((1)D2), and C((3)P2) + O((3)PJ): C((3)P2) + O((1)D2), which were determined based on the time-slice VMI-PI measurements of C(+) ions formed by J-state selective photoionization sampling of C((3)P(0,1,2)), also reveal strong dependences on the spin-orbit state of C((3)P(0,1,2)). By combining the measured branching ratios and fine-structure distributions of C((3)P(0,1,2)), we have determined the correlated distributions of C((3)P(0,1,2)) accompanying the formation of O((1)D2) and O((3)P(J)) produced in the VUV photodissociation of CO. The success of this demonstration experiment shows that the VUV photodissociation pump-VUV photoionization probe method is promising for state-to-state photodissociation studies of many small molecules, which are relevant to planetary atmospheres as well as fundamental understanding of photodissociation dynamics.

A HIGH-RESOLUTION PHOTOIONIZATION AND PHOTOELECTRON STUDY OF58Ni USING A VACUUM ULTRAVIOLET LASER

In order to provide high-resolution spectroscopic data of nickel (58Ni) and its cation (58Ni+) for the assignment of vacuum ultraviolet (VUV) stellar spectra, we have obtained the photoionization efficiency (PIE) spectra of 58Ni by using a supersonically cooled laser ablation transition-metal beam source and a broadly tunable VUV laser in the range of 61,100-73,600 cm–1, covering the photoionization transitions: Ni+ (3d 9 2 D) ← Ni (3d 84s 2 3 D), Ni+(3d 9 2 D) ← Ni(3d 84s 2 3 F), and Ni+ (3d 84s 4 F) ← Ni(3d 84s 2 3 F). We have also measured the VUV laser pulsed-field-ionization-photoelectron (PFI-PE) spectra of 58Ni in these regions. The VUV-PFI-PE measurement has allowed the determination of a precise value of 61,619.89 ± 0.8 cm–1 (7.6399 ± 0.0001 eV) for the ionization energy (IE) of 58Ni. Due to the narrow VUV laser optical bandwidth of 0.4 cm–1 used in the present study, many complex autoionizing resonances exhibiting Fano line shape profiles are resolved in the PIE spectra. Four autoionizing Rydberg series originating from two-electron and one-electron excitations from the Ni(3d 84s 2 3 F 4) ground state to converge to the respective Ni+(2 D 3/2) and Ni+(4 FJ ) (J = 9/2, 7/2, and 5/2) ion states are identified. The Rydberg analysis, along with VUV-PFI-PE measurements, has yielded highly precise IE values for the formation of these excited ionic states from the Ni(3d 84s 2 3 F 4) ground state. The IE values, relative photoionization cross sections, and autoionizing Rydberg resonances observed in the present study are relevant to astrophysics by enhancing the atomic database of iron group transition metal atoms and for understanding the Ni and Ni+ contribution to the VUV opacity in the solar atmosphere.

Dissociation dynamics of ion-pair states of Cl2at principal quantum numbers beyond 1500

Long-lived ion-pair states of Cl{sub 2} have been observed by delayed pulsed-field ionization in the vicinity of the Cl{sup -}({sup 1}S{sub 0})+Cl{sup +}({sup 3}P{sub 2}) dissociation threshold following single-photon excitation from the X {sup 1}{Sigma}{sub g}{sup +}(v=0) ground state with a tunable vacuum-ultraviolet laser. The field-ionization spectra reveal a series of resonances corresponding to ion-pair states with effective principal quantum number n* between 1858 and 1876 belonging to a series converging to the Cl{sup -}({sup 1}S{sub 0})+Cl{sup +}({sup 3}P{sub 0}) dissociation threshold. These states are observed by forced predissociation into the Cl{sup -}({sup 1}S{sub 0})+Cl{sup +}({sup 3}P{sub 2}) ion-pair channel. This process is the ion-pair analog of the process of forced autoionization observed in Rydberg states. The analysis of the spectra and of the field-ionization behavior provides information on the couplings between the relevant ionization and dissociation channels and has enabled the determination of the ion-pair dissociation threshold [E{sub IPD}(Cl{sup -}({sup 1}S{sub 0})+Cl{sup +}({sup 3}P{sub 2}))=95 449.8{+-}1.0 cm{sup -1}] and of the dissociation energies of Cl{sub 2} [D{sub 0}(X {sup 1}{Sigma}{sub g}{sup +})=19 998.4{+-}1.1 cm{sup -1}] and Cl{sub 2}{sup +} [D{sub 0}(X{sup +} {sup 2}{Pi}{sub u})=31 942.1{+-}1.5 cm{sup -1}].

Identification of intermediates in an n-heptane/oxygen/argon low-pressure premixed laminar flame using synchrotron radiation

This study was performed with the use of tunable vacuum ultraviolet (VUV) lasers for molecular beam sampling mass spectrometry (MBMS) to detect the intermediates of a premixed n-heptane/oxygen/argon laminar low-pressure flame. In this experiment, 24 intermediate species were identified and quantified by the photoionization mass and efficiency spectra at a stoichiometric mixture of n-heptane/oxygen highly diluted by argon gas. The mole fraction profiles of these species at different flame positions are presented. The results show that the main intermediates are ketone and ether in the initial combustion period and these species then further oxidize to hydrocarbons. Of all the species, the concentrations of ethylene and polycyclic aromatic hydrocarbons (PAHs) are the highest concentration up to 10 −2 and the lowest concentration to 10 −5 in the mole fraction, respectively, at selective flame position. In addition, alkine like propyne exhibits very similar mole fraction profiles with that of benzene in the n-heptane flame. The results provide the strong evidence that benzene production correlates to alkine production in the flame and reinforces, at least qualitatively, the role of propyne species in the benzene formation mechanism. Finally, the distribution of 24 typical species in the flame is correlated with temperature, which is important in establishing the oxidation mechanism of hydrocarbon fuels.

A HIGH-RESOLUTION PHOTOIONIZATION STUDY OF56Fe USING A VACUUM ULTRAVIOLET LASER

The photoionization efficiency (PIE) spectrum for 56Fe formed by laser ablation has been measured using tunable vacuum ultraviolet (VUV) laser radiation in the energy range of 63000–74700 cm−1, covering the threshold regions for the photoionization transitions of Fe+(3d64s6D) ← Fe(3d64s2 5D) and Fe+(3d64s4D) ← Fe(3d64s2 5D). The fact that no step-like structures in the PIE spectrum are observed at these ionization thresholds indicates that direct photoionization plays a very minor role in the photoionization of Fe in this VUV energy range. Comparing the VUV-PIE and the VUV-absorption spectra of Fe shows that all prominent absorption bands of Fe correspond to strong autoionizing structures in the PIE spectrum of Fe. Due to the significantly narrower VUV laser optical bandwidth of 0.12 cm−1 used in the present study, complex autoionizing resonances are resolved in the PIE spectrum. Two autoionizing Rydberg series (3d7 4F7/2)np (n = 9–27) and (3d7 4F9/2)np (n = 10–32) formed by two-electron excitations from the (3d64s2 5D4) ground state are identified to converge to the respective Fe+(3d7 4F7/2) and Fe+(3d7 4F9/2) ion levels. The photoionization cross sections and well resolved autoionizing Rydberg resonances observed in this study are relevant to astrophysics for understanding the Fe contribution to the VUV opacity in the solar atmosphere, and for benchmarking theoretical calculations under the Opacity Project and the IRON Project.

High-resolution Rydberg tagging time-of-flight measurements of atomic photofragments by single-photon vacuum ultraviolet laser excitation

By coupling a comprehensive tunable vacuum ultraviolet (VUV) laser system to a velocity-mapped ion imaging apparatus, we show that high-resolution high-n Rydberg tagging time-of-flight (TOF) measurements of nascent atomic photofragments formed by laser photodissociation can be made using single-photon VUV laser photoexcitation. To illustrate this single-photon Rydberg tagging TOF method, we present here the results of the VUV laser high-n Rydberg tagging TOF measurements of O((3)P(2)) and S((3)P(2)) formed in the photodissociation of SO(2) and CS(2) at 193.3 and 202.3 nm, respectively. These results are compared to those obtained by employing the VUV laser photoionization time-sliced velocity-mapped ion imaging technique. The fact that the kinetic energy resolutions achieved in the VUV laser high-n Rydberg tagging TOF measurements of O and S atoms are found to be higher than those observed in the VUV laser photoionization, time-sliced velocity-mapped ion imaging studies show that the single-photon VUV laser high-n Rydberg tagging TOF method is useful and complementary to state-of-the-art time-sliced velocity-mapped ion imaging measurements of heavier atomic photofragments, such as O and S atoms. Furthermore, the general agreement observed between the VUV laser high-n Rydberg tagging TOF and velocity-mapped ion imaging experiments supports the conclusion that the lifetimes of the tagged Rydberg states of O and S atoms are sufficiently long to allow the reliable determination of state-resolved UV photodissociation cross sections of SO(2) and CS(2) by using the VUV laser high-n Rydberg tagging TOF method.

Vacuum ultraviolet excitation spectroscopy of the autoionizing Rydberg states of atomic sulfur in the 73350–84950cm−1 frequency range

The photoionization efficiency (PIE) spectra of metastable sulfur (S) atoms in the 1 D and 1 S states have been recorded in the 73 350-84 950 cm(-1) frequency range by using a velocity-mapped ion imaging apparatus that uses a tunable vacuum ultraviolet laser as the ionization source. The S(1 D) and S(1 S) atoms are produced by the 193 nm photodissociation of CS2. The observed PIE spectra of S(1 D) and S(1 S) shows 35 autoionizing resonances with little or no contribution from direct photoionization into the S+(4S 3/2)+e(-) ionization continuum. Velocity-mapped ion images of the S+ at the individual autoionizing Rydberg resonances are used to distinguish whether the lower state of the resonance originates from the 1 D, 1 S, or 3P states. The analysis and assignment of the Rydberg peaks revealed 22 new Rydberg states that were not previously known. The autoionization lifetimes tau of the Rydberg states are derived from the linewidths by fitting the lines with the Fano formula. Deviations from the scaling law of tau(n*) proportional to, n*3, where n* is the effective quantum number of the Rydberg state, are observed. This observation is ascribed to perturbations by nearby triplet Rydberg states, which shorten the autoionization lifetimes of the singlet Rydberg levels.

A vacuum ultraviolet laser photoionization and pulsed field ionization study of nascent S(P2,1,3) and S(D21) formed in the 193.3nm photodissociation of CS2

The photoionization efficiency (PIE) and pulsed field ionization-photoion (PFI-PI) spectra for sulfur atoms S(3P2,1,0) and S(1D2) resulting from the 193.3 nm photodissociation of CS2 have been measured using tunable vacuum ultraviolet (vuv) laser radiation in the frequency range of 82 750-83 570 cm(-1). The PIE spectrum of S(3P2,1,0) near their ionization threshold exhibits steplike structures. On the basis of the velocity-mapped ion-imaging measurements, four strong autoionizing peaks observed in the PIE measurement in this frequency range have been identified to originate from vuv excitation of S(1D2). The PFI-PI measurement reveals over 120 previously unidentified new Rydberg lines. They have been assigned as Rydberg states [3p3(4S composite function nd3 D composite function (n=17-64)] converging to the ground ionic state S+(4S composite function) formed by vuv excitations of S(3P2,1,0). The converging limits of these Rydberg series have provided more accurate values, 82 985.43+/-0.05, 83 162.94+/-0.05, and 83 559.04+/-0.05 cm(-1) for the respective ionization energies of S(3P0), S(3P1), and S(3P2) to form S+(4S composite function). The relative intensities of the PFI-PI bands for S(3P0), S(3P1), and S(3P2) have been used to determine the branching ratios for these fine structure states, S(3P0):S(3P1):S(3P2)=1.00:1.54:3.55, produced by photodissociation of CS2 at 193.3 nm.

Study on combustion of gasoline/MTBE in laminar flame with synchrotron radiation

Synchrotron radiation offers important advantages with the use of tunable vacuum ultraviolet (VUV) lasers for molecular beam sampling mass spectrometry (MBMS). These advantages include superior signal-to-noise, soft ionization, and access to photon energies outside the limited tuning ranges of current VUV laser sources. Combining MBMS with tunable synchrotron radiation photoionization, two similar types of fuels, gasoline/oxygen and gasoline/MTBE/oxygen in low-pressure premixed laminar flame were investigated. Photoionization efficiency (PIE) measurements were used to identify the intermediates isomers within flame. The two combustion processes are discussed by comparing the intermediates and their spatial profiles within the two kinds of flame mentioned above.

N(4S) Formation following the 193.3-nm ArF Laser Irradiation of NO and NO2 and Its Application to Kinetic Studies of N(4S) Reactions with NO and NO2

Formation of the ground-state nitrogen atom, N((4)S), following 193.3-nm ArF laser irradiation of NO and NO(2) was detected directly by a technique of laser-induced fluorescence (LIF) spectroscopy at 120.07 nm. Tunable vacuum ultraviolet (VUV) laser radiation around 120.07 nm was generated by two-photon resonance four-wave sum frequency mixing in Hg vapor. Photoexcitation processes of NO and NO(2) giving rise to the N((4)S) formation are discussed on the basis of the Doppler profiles of the nascent N((4)S) atoms produced from the photolysis of NO and NO(2) and the photolysis laser-power dependence of the N((4)S) signal intensities. Using laser flash photolysis and vacuum ultraviolet laser-induced fluorescence detection, the kinetics of the reactions of N((4)S) with NO and NO(2) have been investigated at 295 +/- 2 K. The rate constants for the reactions of N((4)S) with NO and NO(2) were determined to be (3.8 +/- 0.2) x 10(-11) and (7.3 +/- 0.9) x 10(-12) cm(3) molecule(-1) s(-1), respectively, where the quoted uncertainties are 2sigma statistical uncertainty including estimated systematic error.