Autocorrelator for measuring an ultrashort optical pulse width in the ultraviolet region based on two-photon ionization of an organic compound

Ultrafast Photo‐ion Probing of the Ring‐Opening Process in Trans‐Stilbene Oxide

“…The pulse duration of the UV laser was obtained by recording the time‐resolved mass spectra of different gases backfilled into the apparatus via a needle valve, the opening of which was situated near the focus of the pump and probe beams. The gases used were 1,4‐dioxane and xenon, which are ionized via a two‐ and three‐photon nonresonant process, respectively, when using 266 nm photons [46,47] . By recording how the parent ion signal of both samples varied with respect to the pump‐probe delay it was possible to measure the auto‐correlation values for the pulses.…”

“…The gases used were 1,4‐dioxane and xenon, which are ionized via a two‐ and three‐photon nonresonant process, respectively, when using 266 nm photons. [ 46 , 47 ] By recording how the parent ion signal of both samples varied with respect to the pump‐probe delay it was possible to measure the auto‐correlation values for the pulses. A FWHM of (430±10) and (370±10) fs, was measured for the 1,4‐dioxane and xenon, respectively, both of which suggest a pulse duration around 300 fs.…”

A Simple Method for the Evaluation of the Pulse Width of an Ultraviolet Femtosecond Laser Used in Two-Photon Ionization Mass Spectrometry

“…1 µJ. In the experiment, 1,4-dioxane was introduced into the mass spectrometer for recording of a non-resonant two-photon ionization signal [20]. The signal intensity was measured by translating the second prism to alter the positive dispersion in the compressor.…”

“…It should be noted that the three transform-limited pulses are assumed to be superimposed in-phase without any chirp in Equation (20). In contrast, when the laser emissions are not phase-locked to each other (i.e., they are randomly phased), I 2 FRAC (τ = 0) can then be expressed as…”

“…For simple on-site measurement of pulse widths, a device based on fringe-resolved autocorrelation (FRAC) was developed, which consisted of an interferometer and a time-of-flight mass spectrometer that was used as a two-photon-response detector to measure a non-resonant two-photon ionization signal [18][19][20][21]. However, the laser beam must be split into two parts and recombined after the interferometer, which reduces the laser pulse energy and then the sensitivity of the mass spectrometer.…”