?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Stimulated+emission+depletion+dynamics+in+push-push+polyenes&rft.creator=Marsh%2C+RJ&rft.creator=Leonczek%2C+ND&rft.creator=Armoogum%2C+DA&rft.creator=Porres%2C+L&rft.creator=Mongin%2C+O&rft.creator=Blanchard-Desce%2C+M&rft.creator=Bain%2C+AJ&rft.description=Two-photon+fluorescence+polarisation+and+stimulated+emission+depletion+dynamics+are+investigated+in+three+high+two+-photon+cross-section+push-push+polyenes%3A+OM62%2C+LP79+and+OM77+and+compared+to+the+behaviour+of+a+standard+fluorophore+(rhodamine+6G).+Two-photon+fluorescence+anisotropy+measurements+(R(O)+and+Omega)+were+undertaken+using+picosecond+time-correlated+single+photon+counting+(TCSPC).+For+OM62+and+LP79+these+are+consistent+with+a+diagonal+two-dimensional+transition+tensor+with+S-XX%3ES-YY.+For+OM77+the+contribution+of+off-diagonal+elements+(S-XY+%26+S-YX)+appears+significant.+Two-photon+fluorescence+anisotropy+decay+data+is+combined+with+streak+camera+measurements+of+excited+state+population+depletion+to+determine+stimulated+emission+cross+sections+and+ground+state+vibrational+relaxation+times.+Cross-sections+for+STED+in+all+three+polyenes+were+found+to+be+significantly+higher+than+those+for+rhodamine+6G.+The+efficiency+of+STED+is+however+dependent+on+the+degree+to+which+the+S-1--%3ES-0+transition+is+saturated+by+the+DUMP+pulse%3B+this+is+mediated+by+fast+ground+state+vibrational+relaxation.+Of+the+three+polyenes..+LP79+is+seen+to+combine+a+large+stimulated+emission+cross-section+(c.a.+13sigma(r6G))+with+rapid+ground+state+relaxation+(tau(R)%3D240fs).&rft.subject=two-photon+absorption%2C+stimulated+emission+depletion%2C+fluorescence+anisotropy%2C+polarisation+vibrational+relaxation%2C+2-photon+absorption%2C+quadrupolar+chromophores%2C+fluorescence+anisotropy%2C+imaging+microscopy%2C+pull+dipolar%2C+fluorophores%2C+spectroscopy%2C+molecules%2C+states%2C+derivatives&rft.publisher=Society+of+Photo-Optical+Instrumentation+Engineers+(SPIE)&rft.contributor=Andrew%2C+DL&rft.contributor=Cao%2C+GZ&rft.contributor=Gaburro%2C+Z&rft.date=2004-10-14&rft.type=Proceedings+paper&rft.publisher=Conference+on+Nanophotonic+Materials&rft.language=eng&rft.source=+++++In%3A+Andrew%2C+DL+and+Cao%2C+GZ+and+Gaburro%2C+Z%2C+(eds.)+Nanophotonic+Materials.++++Society+of+Photo-Optical+Instrumentation+Engineers+(SPIE)%3A+Denver%2C+CO%2C+USA.+(2004)+++++&rft.format=text&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F36159%2F1%2FBain_117_1_STED_PushPushPolyenes.pdf&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F36159%2F&rft.rights=open