@article{fdi:010054323,
  title = {{S}tudy of near infra red femtosecond laser induced particles using transmission electron microscopy and low pressure impaction : implications for laser ablation-inductively coupled plasma-mass spectrometry analysis of natural monazite},
  author = {{D}'{A}bzac, {F}.{X}. and {S}eydoux-{G}uillaume, {A}.{M}. and {C}hmeleff, {J}. and {D}atas, {L}. and {P}oitrasson, {F}ranck},
  abstract = {{T}he characteristics of infra red femtosecond laser-induced aerosols are studied for monazite ({LREE}, {T}h ({PO}(4))) ablation and correlations are established with inductively coupled plasma-mass spectrometry ({ICP}-{MS}) signals. {C}ritical parameters are tested within wide ranges of values in order to cover the usual laser ablation -{ICP}-{MS} analysis conditions: pulse energy (0.15<{E}(0)<1 m{J}/pulse), pulse width (60<{T}<3000 fs), ablation time (t <= 10 min) and transport length (l <= 6.3 m). {T}ransmission electron microscopy reveals that aerosols are made of agglomerates of -10 nm particles and 20-300 nm phosphorus depleted condensed spherical particles. {T}hese structures are not affected by any laser ablation parameter. {P}article counting is performed using electronic low pressure impaction. {S}mall changes on particle size distribution are noticed. {T}hey may be induced either by a peak of ablation rate in the first 15 s at high fluence (larger particles) or the loss of small particles during transport. {W}e found a positive correlation between {I} ({ICP}-{MS} mean signal intensity in cps) and {N} (particle density in cm(-3)) when varying {E}(0) and t, suggesting that {N} is controlled by the irradiance ({P}(o) in {W}.cm(-2)). {E}lemental ratio measurements show a steady state signal after the initial high ablation rate (mass load effect in the plasma torch) and before a late chemical fractionation, induced by poor extraction of bigger, early condensed spherical particles from the deepening crater. {S}uch chemical fractionation effects remain within uncertainties, however. {T}hese effects can be limited by monitoring {E}(0) to shorten the initial transient state and delay the attainment of an unfavorable crater aspect ratio. {M}ost adopted settings are for the first time deduced from aerosol characteristics, for infra red femtosecond laser ablation. {A} short transport (l<4.0 in) limits the agglomeration of particles by collision process along the tube. {S}hort {T} is preferred because of higher {P}(o), yet no benefit is found on {ICP}-{MS} signal intensity under 200 fs. {U}nder such pulse widths the increased particle production induces more agglomeration during transport, thereby resulting in higher mass load effects that reduce the ionization efficiency of the plasma torch. {T}hus, pulse energy must be set to get an optimal balance between the need for a high signal/background ratio and limitation of mass load effects in the plasma torch.},
  keywords = {{L}aser ablation ; {A}erosol ; {P}article counting ; {ICP}-{MS} ; {C}hemical fractionation},
  journal = {{S}pectrochimica {A}cta {P}art {B}. {A}tomic {S}pectroscopy},
  volume = {66},
  numero = {9-10},
  pages = {671--680},
  ISSN = {0584-8547},
  year = {2011},
  DOI = {10.1016/j.sab.2011.09.010},
  URL = {http://www.documentation.ird.fr/hor/fdi:010054323},
}