?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%2F7412%2F&rft.title=SCANNING+NEAR-FIELD+OPTICAL+MICROSCOPY+FOR+MEASURING+MATERIALS+PROPERTIES+AT+THE+NANOSCALE&rft.creator=Stebounova%2C+Larissa+V&rft.description=Apertureless+scanning+near-field+optical+microscopy+is+a+valuable+tool+for+characterization+of+chemical+and+spectroscopic+properties+of+the+materials+at+the+nanoscale.+Description+of+apertureless+near-field+microscope+is+provided+along+with+the+description+of+a+homodyne+detection+of+the+near-field+signal+which+allows+enhancing+of+a+weak+scattered+radiation.+Experimental+evidences+that+homodyne+detection+markedly+improves+the+signal-to-noise+ratio+of+the+detected+signal+are+presented.+A+model+for+the+dependence+of+the+near+field+signal%2C+as+a+function+of+the+normal+distance+of+the+tip+from+the+surface%2C+is+discussed.+Application+of+a+model+in+which+the+tip+is+represented+by+two+spherical+scatterers%2C+one+large+and+one+small%2C+indicates+the+electromagnetic+field+enhancement+is+90+fold+greater+at+the+sharp+apex+of+metallic+probe+tip.Apertureless+near-field+scanning+infrared+microscopy+was+employed+to+study+samples+patterned+with+regions+of+DNA+and+hexadecanethiol.+Chemical+contrast+imaging+was+achieved+by+examining+IR+absorption+in+the+spectral+region+of+the+phosphate+stretching+band+of+DNA+molecules+and+harmonic+demodulation+of+the+signal+scattered+by+the+oscillating+probe.+IR+absorption+maps+revealed+that+the+IR+signal+was+not+coupled+to+the+vertical+tip+motion%2C+indicating+artifact-free+imaging.+Monolayer-sensitive+chemical+imaging+with+a+lateral+spatial+resolution+of+approximately+200+nm+is+demonstrated.The+field+enhancement+in+very+small+aperture+lasers+was+studied+using+apertureless+near-field+microscopy.+The+near-field+optical+pattern+around+the+aperture+indicates+the+interference+of+surface+plasmons+with+incident+light.+A+surface+plasmon+point-source+model+has+been+used+to+determine+the+wavelength+and+the+decay+length+of+surface+plasmons+at+the+Al%2Fsilicon+nitride+interface.+Near-field+measurements+also+confirmed+a+preferred+orientation+of+the+rectangular+aperture+waveguide+for+the+signal+enhancement+in+very+small+aperture+lasers.Optical+field+confinement+in+a+ridge+waveguide+nanostructure+designed+for+ultrahigh-density+recording+was+observed+using+an+apertureless+near-field+scanning+optical+microscope.+The+aperture+was+fabricated+on+a+commercial+edge-emitting+semiconductor+laser+as+the+light+source.+The+emission+patterns+are+in+agreement+with+theoretical+simulation+of+such+structures.+A+90+nm+x+70+nm+full-width-half-maximum+spot+size+was+measured+and+is+comparable+to+the+ridge+width+of+the+aperture.&rft.date=2005-06-06&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%2F7412%2F1%2Fstebounova_edt2005.pdf&rft.identifier=++Stebounova%2C+Larissa+V++(2005)+SCANNING+NEAR-FIELD+OPTICAL+MICROSCOPY+FOR+MEASURING+MATERIALS+PROPERTIES+AT+THE+NANOSCALE.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++