Investigation of laser sputtering of iron at low fluence using resonance ionization mass spectrometry

Abstract

Emission of neutral and ionized Fe atoms induced by N2 laser irradiation (λ=337 nm) of iron targets was investigated for laser fluences ranging from the sputtering threshold (a few tens mJ/cm2) up to 320 mJ/cm2. The unique sensitivity of resonance ionization mass spectrometry permitted to identify the laser-sputtered neutral particles, to study their velocity distribution and excitation state, and to measure the laser-sputtering yield at a very low emission level (100 Fe atoms removed per laser shot). In this soft ablation mode, it appears that the sputtered atoms carry direct information on the primary mechanisms involved in the laser sputtering of an iron surface. The present study corroborates a thermal process in which the laser beam acts as a pulsed heat source. Energy characteristics of the emitted neutral atoms reflect rather well the thermal state of the surface, the atom temperature increasing from the ambient at threshold to melting and boiling temperatures for growing laser energies.

Soft laser sputtering of GaAs semiconductor surfaces

“…The TOF distributions of Ga° atoms and (As°)As 2° molecules are well fitted by half-space Maxwellian distributions characterized by kinetic temperatures. 1 They are in broad agreement with the results obtained from a model of laser heating of the surface. In the conditions of soft laser sputtering, the energy of the sputtered particles reflects the "thermal" state of the surface.…”

Resonant ionization of laser desorbed silicon

“…Our case is different because of the unique sensitivity of the RIMS method. As previously shown, on this setup the limit of detection is about 100 atoms, 15 corresponding to a sensitivity of detection of 1/1000 atomic layer under the laser spot. It is very low and could be considered as the threshold for the desorption process itself.…”

Improved detection sensitivity of elements in solids via laser postionization in laser desorption time‐of‐flight mass spectrometry

“…In the experiments, the desorption laser energies were chosen ranging from 25 to 150 μJ, resulting in the laser irradiance of 0.28–1.7 × 10 8 W/cm 2 at the irradiated area. Generally, specific energy value for desorption is up to solid types, which should be just below the ionization thresholds of solid samples to avoid as less as possible direct ions generated by the incident laser . Discrimination against the detection of direct and post‐ionized ions by LDI and LPI, respectively, can be well solved by adjusting suitable laser energy.…”

“…Generally, specific energy value for desorption is up to solid types, which should be just below the ionization thresholds of solid samples to avoid as less as possible direct ions generated by the incident laser. 53 Discrimination against the detection of direct and post-ionized ions by LDI and LPI, respectively, can be well solved by adjusting suitable laser energy. The desorption laser had an incident angle of 45°with respect to metal targets mounted on a piezoscanner translation stage (SLC-17, SmartAct GmbH, Germany) that permits the target to be moved to a fresh surface every laser pulse.…”