TEA COz laser induced perturbation of shape and intensity of the first Balmer lines emitted by a hydrogen low-pressure glow discharge is investigated for radiation intensity fL in the 10 MW cm-' range. Because of the AC Stark effect, shifts of levels n, = 4, 5, 6, 7 and 8 are measured (i.e. for f~ = 8 MW cm-', AE5 = -0.59 cm-', AEd = 1.81 cm-l, AE7 = 0.55 cm-I). In addition, splitting and optical satellites originating from high orbital quantum numbers are clearly observed on the Ha line. The laser one-and two-photon ionisation processes almost completely depopulate the excited states n, 2 8.Because of collisional radiative processes the states n, = 4, 5, 6 and 7 which do not undergo photoionisation are also strongly depopulated. From a kinetic model, an approximate calculation of the collisional excitation transfer rate coefficient shows that the infrared laser perturbation method can be a powerful tool for investigating collisional excitation transfers connecting excited state populations in plasmas.
We have characterized the absorbing film assisted transfer of Trichoderma longibrachiatum conidia using a synchronized laser for illumination. The transfer laser used was a KrF excimer laser (λ = 248 nm, FWHM = 30 ns) and the ejected material was illuminated parallel to the quartz plate by a nitrogen laser pumped Coumarine 153 dye laser beam (λ = 453 nm, FWHM = 1 ns) electronically delayed relative to the transfer UV pulse. Our time-resolved investigations determined that the ejection velocity front of the conidia plume from the donor surface during the transfer procedure was 1150 m s −1 at 355 mJ cm −2 applied laser fluence. On the basis of the measured data, the acceleration of the emitted conidia at the plume front was approximately 10 9 ×g. The conidia survived the absorbing film assisted forward transfer and associated mechanical shear without significant damages suggesting that the technique might be applicable to other more fragile types of biological objects and applications.
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