Tunable Coherent VUV Radiation Research Articles

Tunable VUV light generation for resonance ionization mass spectrometry of Krypton

Tunable coherent VUV radiation from 115.8 to 116.9nm has been produced by non-linear four-wave sum frequency mixing in a xenon–argon mixture. 116.5nm light generated by this means has been used as the first step in a three color, doubly resonant ionization scheme for Kr. In the process of validating the system the xenon refractive index per atom (STP) at 116.5nm has been determined to be (n(Xe)−1)/NXe=−6.8(±0.8)×10−23cm3.

Generation of tunable coherent VUV radiation by four-wave sum-mixing in Ne

Ne was used as nonlinear optical medium to produce continuously tunable coherent VUV radiation by a lower order nonlinear process; tunable coherent VUV radiation from 116.6 to 119.2 nm has been produced by nonresonant FWSM in Ne. The conversion efficiency was found to be of the same order as that in Ar, and we concluded that the higher efficiency was due to the very small dispersion of Ne. If a higher gas density is achieved, the conversion efficiency is expected to be improved by at least two orders of magnitude.

The generation of tunable coherent VUV radiation by nonresonant four-wave sum-mixing below the first resonance level of Kr and Ar

The generation of tunable coherent VUV radiation by four-wave sum-mixing (FWSM) in the low-energy-side of the first resonance level of nonlinear media was demonstrated for the first time to the authors' knowledge. The small dimension of the Kr and Ar jet provided by a piezoelectric valve eliminated the negative dispersion requirement of the FWSM process to nonlinear media thus the FWSM process in the positive region was observed comparable efficient with that in the negative region. Multi-coherence-length interferences were also observed in the experiment.

He II Balmer series line shifts in a dense z-pinch plasma

Describes measurements of He II Balmer series line shapes and shifts, using both absorption and emission techniques, in a dense (Ne=2+or-0.5*1018 cm-3), cool (Te=3.4 eV) helium z-pinch plasma. Tunable coherent VUV radiation was generated around 1640 AA by Raman up-conversion in H2 and around 1215 AA by frequency tripling in krypton. An absorption measurement was made on the near wing profile of the He II Balmer-alpha line (1640 AA) using the Raman up-converted light source. Emission measurements were made on the He II Balmer-beta (1215 AA) line profile; these were complemented by an accurate wavelength calibration using the tunable coherent VUV light from the frequency tripled light source. A shift in the wavelength of the Balmer-beta line centre of 0.7+or-0.2 AA to the red was observed. Discussion is given of this shift in relation to existing theories of the plasma polarisation shift.

Nonresonant tripling and sum-frequency mixing in Hg

Nonresonant frequency tripling and sum-frequency mixing of pulsed dye-laser radiation generates in Hg vapor continuously tunable coherent vuv radiation in the wavelength range λvuv=132-185nm. Laser pulse powers of 1–2 MW produce vuv light pulses of 0.6–1.5 W (2–4.8×109 photons/pulse).

Coherent VUV generation by resonantly-enhanced nonlinear frequency mixing in Cd vapor

Broadly tunable coherent VUV radiation has been generated by two-photon resonant sum-frequency mixing in Cd vapor, using frequency-doubled Nd:YAG laser-pumped dye lasers and the three two-photon resonances 5^{1}S_{0} - 5^{1}D_{2}, - 7^{1}S_{0} , and -6^{1}D_{2} . The generated VUV having no spectral structure covers a wavelength range of 119.6-136.8 nm, and the VUV generation efficiency has been measured as a function of wavelength. Besides the tunable VUV, additional intense VUV lines were observed in a spectral range of 145.3-171.1 nm, which were generated by four-wave parametric and second-harmonic processes. The generation mechanisms of these VUV lines are discussed.

Generation of tunable coherent VUV radiation by anti-Stokes Raman scattering of excimer-pumped dye laser radiation

A straightforward method of generating tunable coherent VUV radiation is described. Radiation down to 1362 Å was produced by Raman shifting the output of a commercially produced, excimer-pumped dye laser system. It is shown that generation of VUV radiation at 1640 Å is more efficient using the 8th anti-Stokes line from a UV dye than by using the 10th anti-Stokes line from a visible dye which had twice the output power.

Vacuum-ultraviolet laser-excited spectra of Xe_2

Fluorescence excitation of Xe(2) at 149.0 nm has been observed using a pulsed supersonic jet for dimer formation and cooling and using tunable coherent VUV radiation from four-wave mixing in Mg vapor for excitation. The resolved vibronic structure resulting from isotopic Xe(2) molecules has yielded unambiguous vibrational numbering (upsilon'=37-46), giving the following constants for the first O(+)(u) excited state of Xe(2): T(e) = 63 796(6) cm (-1), omega'(e) = 124.86(30) cm(-1), omega(e)X'(e) = 0.937(3) cm(-1), and D(e) = 4446(7) cm(-1).