Third-harmonic generation in argon, krypton, and xenon: Bandwidth limitations in the vicinity of Lyman-α

Mahon, Rita; McIlrath, T. J.; Myerscough, V P; Koopman, David W.

doi:10.1109/jqe.1979.1070036

Cited by 163 publications

(68 citation statements)

References 14 publications

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“…50 VUV light of wavelength 118.2 nm (hereafter referred to as 118 nm) was produced by tripling the 354.7 nm (hereafter referred to as 355 nm) third harmonic of a Nd:YAG laser (Continuum Surelite I, ~10-20 mJ per 5 ns pulse) in a phasematched Xe/Ar gas mixture. [36][37][38][39] The 355 nm laser beam was 55 tightly focused into a gas cell containing a mixture of Xe (BOC, >99.9%) and Ar (BOC, >99.9%) in a ratio of 1:11. The 118 nm and residual 355 nm light were not separated before entering the imaging chamber, and in some of the experiments the latter was used to effect photolysis of the parent cation of interest.…”

Section: Methodsmentioning

confidence: 99%

Fragmentation dynamics of the ethyl bromide and ethyl iodide cations: a velocity-map imaging study

Gardiner

Karsili

Lipciuc

et al. 2014

Phys. Chem. Chem. Phys.

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The photodissociation dynamics of ethyl bromide and ethyl iodide cations (C 2 H 5 Br + and C 2 H 5 I + ) have been studied. Ethyl halide cations were formed through vacuum ultraviolet (VUV) photoionization of the respective neutral parent molecules at 118.2 nm, and were photolysed at a number of ultraviolet (UV) photolysis wavelengths, including 355 nm and wavelengths in the range from 236 to 266 nm. Time-offlight mass spectra and velocity-map images have been acquired for all fragment ions and for ground (Br) and spin-orbit excited (Br*) bromine atom products, allowing multiple fragmentation pathways to be investigated. The experimental studies are complemented by spin-orbit resolved ab initio calculations of cuts through the potential energy surfaces (along the R C-Br/I stretch coordinate) for the ground and first few excited states of the respective cations. Analysis of the velocity-map images indicates that photoexcited C 2 H 5 Br + cations undergo prompt C-Br bond fission to form predominantly C 2 H 5 + + Br* products with a near-limiting 'parallel' recoil velocity distribution. The observed C 2 H 3 + + H 2 + Br product channel is thought to arise via unimolecular decay of highly internally excited C 2 H 5 + products formed following radiationless transfer from the initial excited state populated by photon absorption. Broadly similar behaviour is observed in the case of C 2 H 5 I + , along with an additional energetically accessible C-I bond fission channel to form C 2 H 5 + I + products. HX (X = Br, I) elimination from the highly internally excited C 2 H 5 X + cation is deemed the most probable route to forming the C 2 H 4 + fragment ions observed from both cations. Finally, both ethyl halide cations also show evidence of a minor C-C bond fission process to form CH 2 X + + CH 3 products.dissociation limit involves CH 3 + + Br* products, whereas for CH 3 I + , the larger spin-orbit splitting in atomic iodine relative

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Section: Methodsmentioning

confidence: 99%

Fragmentation dynamics of the ethyl bromide and ethyl iodide cations: a velocity-map imaging study

Gardiner

Karsili

Lipciuc

et al. 2014

Phys. Chem. Chem. Phys.

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“…[7][8][9][10][11][12][13] Research and development for generation of VUV and L-α radiation by laser wave mixing in gases has been continued over few decades generating many significant advances. [14][15][16][17][18][19][20][21][22][23] In continuing this work we could recently achieve high-efficiency operation with high beam quality in ns pulsed generation of hydrogen L-α radiation by using the high-intensity input radiation and avoiding the onset of the full-scale discharge of Kr-Ar gas in the laser focus. 24 For generation of L-α radiation by the four-wave mixing with initiated photoionization effects in Kr-Ar mixture shown in Fig.1 the output intensity of L-α radiation can be expressed via the input intensities (I 1 and I 2 ) as follows 1 where N Kr is the Kr density, χ a is the third order nonlinear atomic susceptibility of Kr and F is the dephasing factor.…”

Section: Introductionmentioning

confidence: 99%

Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

et al. 2016

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We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α) radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i) multi-photon ionization, (ii) step-wise (2+1)-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii) laser-induced avalanche ionization produced by generated free electrons. Developed expressions validated by order of magnitude estimations and available experimental data allow us to identify the area for the operation under high input laser intensities avoiding the onset of full-scale discharge, loss of efficiency and inhibition of generated L-α radiation. Calculations made reveal an opportunity for scaling up the output energy of the experimentally generated pulsed L-α radiation without significant enhancement of photoionization.

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“…Calculations of C have been performed for Kr and Xe (Mahon et al 1979), yielding the results displayed in Figure 2. Negative dispersion in atoms (shown in gray-shaded areas in Figure 2) is known to occur in the energy range just above the allowed transitions, and this is reflected in the figure.…”

Section: Phase Matching In the Tight-focus Limitmentioning

confidence: 99%

Precision Laser Spectroscopy in the Extreme Ultraviolet

Eikema

Ubachs

2011

Handbook of High‐resolution Spectroscopy

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Techniques for the production of short wavelengths in the extreme ultraviolet wavelength range are described, spanning low‐order harmonic generation in the perturbative regime for narrow bandwidth XUV production to the plateau‐regime with the three‐step collisional model for the generation of high harmonics with broadband ultrafast pulses. In addition, the intermediate regime is discussed for pulses of 300 ps duration, as well as the regime of harmonic conversion based on continuous wave lasers aiming at the production of coherent Lyman‐α radiation. Applications of XUV sources in the frequency domain typically rely on the production of XUV‐light from narrowband Fourier‐transform‐limited pulses for recording high‐resolution spectra. Alternatively, harmonically upconverted pulses of ultrashort duration (with inter‐pulse coherence) can be used for spectroscopic studies in the time and frequency domain (such as direct frequency comb spectroscopy techniques). Examples of both approaches for atomic and molecular spectroscopy are discussed at some length. For precision metrology on atomic systems, a focus is put on the Lamb shift determination in the He ground state. In the realm of molecular spectroscopy, predissociation phenomena in the nitrogen molecule are highlighted, with relevance for dissociation processes occurring in the upper layers of the Earth atmosphere. Similar predissociation phenomena in carbon monoxide are also treated in some detail, in this case with relevance for the chemistry in interstellar clouds. Precision XUV spectroscopy of molecular hydrogen is discussed as well, as it relates to the possibility of detecting a variation of the proton–electron mass ratio on a cosmological time scale. In the last section, applications of direct frequency comb spectroscopic techniques at short wavelengths are explained and prospects are given for using these techniques at extreme ultraviolet wavelengths.

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Third-harmonic generation in argon, krypton, and xenon: Bandwidth limitations in the vicinity of Lyman-α

Cited by 163 publications

References 14 publications

Fragmentation dynamics of the ethyl bromide and ethyl iodide cations: a velocity-map imaging study

Fragmentation dynamics of the ethyl bromide and ethyl iodide cations: a velocity-map imaging study

Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

Precision Laser Spectroscopy in the Extreme Ultraviolet

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