(Color online) Side view of the mechanical setup for implementing kilohertz laser ablation into the helium droplet machine. The ablation laser beam enters the nozzle chamber from above through an entrance window mounted on a gate valve (5) and is focused onto the sample rod. The helium droplet beam propagates normal to the paper plane through the skimmer [dashed circle, (7)] right above the target rod. The main technical features are (1) a translation stage mounted upside down, (2) a rotary feedthrough, (3) a bellow chamber serving as vacuum lock and for aligning the sample, [(4) and (5)] gate valves, and (6) a motor coupled to a translation stage which moves the focusing lens back and forth. The inset shows the metal sheets that cover the direct line of sight from the ablation spot to nozzle and skimmer orifices.
(Color online) Time-of-flight signal traces of helium nanodroplets doped with Mg for two different laser pulse energies of the Nd:YAG laser operated at repetition rate. The signal is measured using a quadrupole mass spectrometer set to a mass of .
(Color online) Dependence of the yield of ionized Mg monomers and dimers as a function of laser pulse energy. Inset: time-of-flight signal traces of Mg doped droplets recorded at the mass of the Mg monomer, dimer, and trimer.
Amplitude of the doping signal as a function of the position of the focusing lens for low (a) and moderate (b) pulse energies. Amplitude of the signal drop due to beam destruction at moderate pulse energies (c).
(Color online) Amplitudes of the laser doping signal as a function of laser pulse energy at the lens position of the maximum doping by desorption (circles) and in focus (triangles).
(Color online) Spectrum of helium nanodroplets doped with Li atoms by means of laser ablation (red line) in comparison with oven doping.
(Color online) Yield of various metal monomers (a) and dimers (b) detected by the QMS as a function of vaporization energy (Ref. 26).
(Color online) Yield of guanine and guanine oligomers doped in helium nanodroplets by laser ablation.
(Color online) Yield of small carbon clusters doped in helium nanodroplets by ablation of a graphite sample.
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