TY - JOUR
T1 - Intracluster reaction, fragmentation, and structure of monomethylamine, dimethylamine, and trimethylamine cluster ions
AU - Tzeng, W. B.
AU - Narayanan, K.
AU - Chang, G. C.
AU - Tsai, W. C.
AU - Ho, J. J.
PY - 1996/9/19
Y1 - 1996/9/19
N2 - Ammonia, monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) clusters, formed in a supersonic expansion, were investigated using a multiphoton ionization time-of-flight mass spectrometer. The observed major product ions resulting from prompt fragmentation following ionization are (NH3)nH+, (CH3NH2)nH+, [(CH3)2NH]nH+, and [(CH3)3N]nH+. Detection of stable CH2=NH2+ and (CH2=NH-CH3)+ immonium ions and other fragments provides evidence for molecular rearrangement and fragmentation within our observable time windows. Anomalously large relative intensities observed for (NH3)5H+, (CH3NH2)4H+, [(CH3)2NH]3H+, and [(CH3)3N]2H+ are attributed to enhanced stability of the cluster ions, due to the complete filling of hydrogen-bonding sites on the "central ions". Fully optimized geometries and stabilization energies of these cluster ions have been predicted using ab initio molecular orbital methods. The experimental findings are in very good agreement with the calculated results.
AB - Ammonia, monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) clusters, formed in a supersonic expansion, were investigated using a multiphoton ionization time-of-flight mass spectrometer. The observed major product ions resulting from prompt fragmentation following ionization are (NH3)nH+, (CH3NH2)nH+, [(CH3)2NH]nH+, and [(CH3)3N]nH+. Detection of stable CH2=NH2+ and (CH2=NH-CH3)+ immonium ions and other fragments provides evidence for molecular rearrangement and fragmentation within our observable time windows. Anomalously large relative intensities observed for (NH3)5H+, (CH3NH2)4H+, [(CH3)2NH]3H+, and [(CH3)3N]2H+ are attributed to enhanced stability of the cluster ions, due to the complete filling of hydrogen-bonding sites on the "central ions". Fully optimized geometries and stabilization energies of these cluster ions have been predicted using ab initio molecular orbital methods. The experimental findings are in very good agreement with the calculated results.
UR - http://www.scopus.com/inward/record.url?scp=0000527367&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0000527367&partnerID=8YFLogxK
U2 - 10.1021/jp961303b
DO - 10.1021/jp961303b
M3 - Article
AN - SCOPUS:0000527367
VL - 100
SP - 15340
EP - 15345
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
SN - 0022-3654
IS - 38
ER -