The positive ion chemistry occurring in silane/nitrogen trifluoride gaseous mixtures has been investigated by ion trap mass spectrometry. Reaction sequences and rate constants have been determined for the processes involving the primary ions SiHn+ (n = 0–3) and NFx+ (x = 1–3) and the secondary ions obtained from their reactions with SiH4 and NF3. The SiHn+ efficiently react with NF3 and undergo cascades of abstraction and scrambling reactions which form the fluorinated and perfluorinated cations SiHFm+ (m = 1, 2), SiH2F+ and SiFx+ (x = 0–3). Fluorinated Si2-clusters such as Si2H2F+, Si2H3F+ and Si2H5F+ were also observed. The reaction of both SiH3+ and SiH2F+ with NF3 produces the elusive fluoronitrenium ion NHF+. Any NFx+ reacts with SiH4 mainly by charge transfer. Additional ionic products are, however, observed which suggest intimate reaction complexes. Worth mentioning is the formation of SiNH2+ from the reaction of both NF+ and NHF+ with SiH4. The primary ions NF2+ and SiH2+ are also “sink” species in our observed chemistry.

Positive ion chemistry of SiH4/NF3 gaseous mixtures studied by ion trap mass spectrometry

ANTONIOTTI, Paola;OPERTI, Lorenza;RABEZZANA, Roberto;TURCO, Francesca;
2009-01-01

Abstract

The positive ion chemistry occurring in silane/nitrogen trifluoride gaseous mixtures has been investigated by ion trap mass spectrometry. Reaction sequences and rate constants have been determined for the processes involving the primary ions SiHn+ (n = 0–3) and NFx+ (x = 1–3) and the secondary ions obtained from their reactions with SiH4 and NF3. The SiHn+ efficiently react with NF3 and undergo cascades of abstraction and scrambling reactions which form the fluorinated and perfluorinated cations SiHFm+ (m = 1, 2), SiH2F+ and SiFx+ (x = 0–3). Fluorinated Si2-clusters such as Si2H2F+, Si2H3F+ and Si2H5F+ were also observed. The reaction of both SiH3+ and SiH2F+ with NF3 produces the elusive fluoronitrenium ion NHF+. Any NFx+ reacts with SiH4 mainly by charge transfer. Additional ionic products are, however, observed which suggest intimate reaction complexes. Worth mentioning is the formation of SiNH2+ from the reaction of both NF+ and NHF+ with SiH4. The primary ions NF2+ and SiH2+ are also “sink” species in our observed chemistry.
2009
15
209
220
http://www.impublications.com/abstract/E15_0209
cationic silicon fluorides; gas-phase ion chemistry; ion trap mass spectrometry; nitrogen trifluoride; silane
Paola Antoniotti; Lorenza Operti; Roberto Rabezzana; Francesca Turco; Stefano Borocci; Felice Grandinetti
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/59650
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