?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F8564%2F&rft.title=Physical+Adsorption+on+Single+Wall+Carbon+Nanotubes&rft.creator=Kondratyuk%2C+Petro&rft.description=The+adsorption+of+molecules+on+single+wall+carbon+nanotubes+in+the+regime+of+physical+adsorption+was+investigated+by+means+of+temperature+programmed+desorption+(TPD)+and+infrared+spectroscopy+under+ultrahigh+vacuum+conditions.+Three+adsorption+sites+could+be+resolved+in+the+TPD+spectra+of+a+number+of+molecules%2C+such+as+CCl4%2C+normal+alkanes+with+5-9+carbon+atoms+in+the+chain%2C+and+an+unsaturated+hydrocarbon%2C+1-heptene.+The+resolution+of+spectral+features+in+the+TPD+spectra+is+especially+pronounced+in+the+case+of+normal+alkane+molecules.+By+comparison+with+theoretical+simulations%2C+these+three+adsorption+sites+were+shown+to+correspond+to%3A+(1)+to+the+nanotube+interior%3B+(2)+the+groove+sites+between+adjacent+nanotubes+on+the+outside+of+the+nanotube+bundles%3B+and+(3)+the+exterior+surface+of+the+nanotubes.+The+nanotube+interior+has+the+highest+binding+energy%2C+followed+by+the+groove+sites+and+exterior+sites.+When+two+different+adsorbates%2C+such+as+CCl4+and+n-C9H20%2C+are+coadsorbed+on+nanotubes%2C+the+adsorbate+with+higher+polarizability+(n-nonane)+occupies+the+more+highly-binding+adsorption+sites%2C+qualitatively+displacing+the+other+adsorbate+to+sites+with+lower+binding+energies.+By+studying+the+dependence+of+the+capacity+of+the+adsorption+sites+on+the+shape+and+length+of+the+adsorbed+molecules%2C+it+was+shown+that+linear+groove+sites+behave+as+a+one-dimensional+adsorption+space.+In+contrast%2C+the+interior+adsorption+sites%2C+which+have+diameters+substantially+larger+than+the+size+of+the+typical+adsorbate+molecules%2C+behaved+as+a+three-dimensional+adsorption+space.+When+1-heptene+confined+inside+nanotubes+was+subjected+to+a+flux+of+an+aggressive+chemical+agent%2C+atomic+H%2C+it+was+seen+that+the+rate+of+reaction+was+3-4+times+slower+compared+to+1-heptene+on+the+exterior+of+the+nanotubes.+This+demonstrates+that+the+nanotube+walls+can+provide+shielding+for+interior-adsorbed+species.+Infrared+spectroscopy+showed+that+the+%C3%AD3+vibrational+mode+of+CF4+(the+mode+with+the+highest+transition+dipole+moment)+shifts+to+lower+frequency+upon+adsorption+on+carbon+nanotubes.+The+shift+is+greatest+for+the+internally-adsorbed+species+(35+cm-1)%2C+while+the+exterior-adsorbed+CF4+shows+a+shift+of+15+cm-1.+This+points+at+the+stronger+van+der+Waals+interaction+when+the+molecule+is+adsorbed+in+the+interior.&rft.date=2007-09-19&rft.type=University+of+Pittsburgh+ETD&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F8564%2F1%2FP_Kondratyuk_2007.pdf&rft.identifier=++Kondratyuk%2C+Petro++(2007)+Physical+Adsorption+on+Single+Wall+Carbon+Nanotubes.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++