The journal of physical chemistry. C, Nanomaterials and interfaces最新文献

{"title":"Electron Beam-Induced Writing of Nanoscale Iron Wires on a Functional Metal Oxide.","authors":"Florian Vollnhals,&nbsp;Tom Woolcot,&nbsp;Marie-Madeleine Walz,&nbsp;Steffen Seiler,&nbsp;Hans-Peter Steinrück,&nbsp;Geoff Thornton,&nbsp;Hubertus Marbach","doi":"10.1021/jp405640a","DOIUrl":"https://doi.org/10.1021/jp405640a","url":null,"abstract":"<p><p>Electron beam-induced surface activation (EBISA) has been used to grow wires of iron on rutile TiO₂(110)-(1 × 1) in ultrahigh vacuum. The wires have a width down to ∼20 nm and hence have potential utility as interconnects on this dielectric substrate. Wire formation was achieved using an electron beam from a scanning electron microscope to activate the surface, which was subsequently exposed to Fe(CO)₅. On the basis of scanning tunneling microscopy and Auger electron spectroscopy measurements, the activation mechanism involves electron beam-induced surface reduction and restructuring.</p>","PeriodicalId":520808,"journal":{"name":"The journal of physical chemistry. C, Nanomaterials and interfaces","volume":" ","pages":"17674-17679"},"PeriodicalIF":3.7,"publicationDate":"2013-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/jp405640a","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40264791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linear and Nonlinear Optical Properties of Photoresponsive [60]Fullerene Hybrid Triads and Tetrads with Dual NIR Two-Photon Absorption Characteristics.","authors":"Seaho Jeon,&nbsp;Joy Haley,&nbsp;Jonathan Flikkema,&nbsp;Venkatram Nalla,&nbsp;Min Wang,&nbsp;Matthew Sfeir,&nbsp;Loon-Seng Tan,&nbsp;Thomas Cooper,&nbsp;Wei Ji,&nbsp;Michael R Hamblin,&nbsp;Long Y Chiang","doi":"10.1021/jp405424q","DOIUrl":"https://doi.org/10.1021/jp405424q","url":null,"abstract":"Two C60-(antenna)x analogous compounds having branched hybrid triad C60(>DPAF-C18)(>CPAF-C2M) and tetrad C60(>DPAF-C18)(>CPAF-C2M)2 nanostructures were synthesized and characterized. The structural design was intended to facilitate the ultrafast fs intramolecular energy-transfer from photoexcited C60[>1(DPAF)*-C18](>CPAF-C2M)1or2 or C60(>DPAF-C18)[>1(CPAF)*-C2M]1or2 to the C60> cage moiety upon two-photon pumping at either 780 or 980 nm, respectively. The latter nanostructure showed approximately equal extinction coefficients of optical absorption over 400-550 nm that corresponds to near-IR two-photon based excitation wavelengths at 780-1100 nm for broadband nonlinear optical (NLO) applications. Aside from their enhanced two-photon absorption (2PA) activity at 780 nm, we also demonstrated ultrafast photo-responses at 980 nm showing 2PA cross-section (σ2) values of 995-1100 GM for the hybrid tetrad. These σ2 values were correlated to the observed good efficiency in reducing fs light-transmittance down to 35% at the light intensity of 110 GW/cm2. Accordingly, 2PA characteristics of these nanostructures at multiple NIR wavelengths provided support for their suitability in uses as broadband NLO nanomaterials at 600-1100 nm that includes the 2PA ability of two antenna, DPAF (700-850 nm) and CPAF (850-1100 nm), and the fullerene cage at shorter wavelengths (600-700 nm).","PeriodicalId":520808,"journal":{"name":"The journal of physical chemistry. C, Nanomaterials and interfaces","volume":" ","pages":"17186-17195"},"PeriodicalIF":3.7,"publicationDate":"2013-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/jp405424q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40270319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface-Supported Hydrocarbon π Radicals Show Kondo Behavior.","authors":"Stefan Müllegger,&nbsp;Mohammad Rashidi,&nbsp;Michael Fattinger,&nbsp;Reinhold Koch","doi":"10.1021/jp310316b","DOIUrl":"https://doi.org/10.1021/jp310316b","url":null,"abstract":"<p><p>Stable hydrocarbon radicals are utilized as spin standards and prototype metal-free molecular magnets able to withstand ambient conditions. Our study presents experimental results obtained with submolecular resolution by scanning tunneling microscopy and spectroscopy from monomers and dimers of stable hydrocarbon π radicals adsorbed on the Au(111) surface at 7-50 K. We provide conclusive evidence of the preservation of the radical spin-1/2 state, aiming to establish α,γ-bisdiphenylene-β-phenylallyl (BDPA) on Au(111) as a novel Kondo system, where the impurity spin is localized in a metal-free π molecular orbital of a neutral radical state in gas phase preserved on a metal support.</p>","PeriodicalId":520808,"journal":{"name":"The journal of physical chemistry. C, Nanomaterials and interfaces","volume":" ","pages":"5718-5721"},"PeriodicalIF":3.7,"publicationDate":"2013-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/jp310316b","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40234693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Porphyrins-Functionalized Single-Walled Carbon Nanotubes Chemiresistive Sensor Arrays for VOCs.","authors":"Mahendra D Shirsat, Tapan Sarkar, James Kakoullis, Nosang V Myung, Bharatan Konnanath, Andreas Spanias, Ashok Mulchandani","doi":"10.1021/jp210582t","DOIUrl":"10.1021/jp210582t","url":null,"abstract":"<p><p>Single-walled carbon nanotubes (SWNTs) have been used extensively for sensor fabrication due to its high surface to volume ratio, nanosized structure and interesting electronic property. Lack of selectivity is a major limitation for SWNTs-based sensors. However, surface modification of SWNTs with a suitable molecular recognition system can enhance the sensitivity. On the other hand, porphyrins have been widely investigated as functional materials for chemical sensor fabrication due to their several unique and interesting physico-chemical properties. Structural differences between free-base and metal substituted porphyrins make them suitable for improving selectivity of sensors. However, their poor conductivity is an impediment in fabrication of prophyrin-based chemiresistor sensors. The present attempt is to resolve these issues by combining freebase- and metallo-porphyrins with SWNTs to fabricate SWNTs-porphyrin hybrid chemiresistor sensor arrays for monitoring volatile organic carbons (VOCs) in air. Differences in sensing performance were noticed for porphyrin with different functional group and with different central metal atom. The mechanistic study for acetone sensing was done using field-effect transistor (FET) measurements and revealed that the sensing mechanism of ruthenium octaethyl porphyrin hybrid device was governed by electrostatic gating effect, whereas iron tetraphenyl porphyrin hybrid device was governed by electrostatic gating and Schottky barrier modulation in combination. Further, the recorded electronic responses for all hybrid sensors were analyzed using a pattern-recognition analysis tool. The pattern-recognition analysis confirmed a definite pattern in response for different hybrid material and could efficiently differentiate analytes from one another. This discriminating capability of the hybrid nanosensor devices open up the possibilities for further development of highly dense nanosensor array with suitable porphyrin for E-nose application.</p>","PeriodicalId":520808,"journal":{"name":"The journal of physical chemistry. C, Nanomaterials and interfaces","volume":" ","pages":"3845-3850"},"PeriodicalIF":0.0,"publicationDate":"2012-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3292351/pdf/nihms352254.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40142557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ensemble and Single Molecule Studies on the Use of Metallic Nanostructures to Enhance the Intrinsic Emission of Enzyme Cofactors.","authors":"Mustafa H Chowdhury, Joseph R Lakowicz, Krishanu Ray","doi":"10.1021/jp112255j","DOIUrl":"10.1021/jp112255j","url":null,"abstract":"<p><p>We present a strategy for enhancing the intrinsic emission of the enzyme cofactors flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN) and nicotinamide adenine dinucleotide (NADH). Ensemble studies show that silver island films (SIFs) are the optimal metal enhanced fluorescence (MEF) substrates for flavins and gave emission enhancements of over 10-fold for both FAD and FMN. A reduction in the lifetime of FAD and FMN on SIFs was also observed. Thermally evaporated aluminum films on quartz slides were found to be the optimal MEF substrate for NADH and gave a 5-fold increase in the emission intensity of NADH. We present finite-difference time-domain (FDTD) calculations that compute the enhancement in the radiated power emitting from an excited state dipole emitting in the wavelength range of NADH in close proximity to an aluminum nanoparticle, and a dipole emitting in the emission wavelength of flavins next to a silver nanoparticle. These calculations confirm that aluminum serves as the optimal MEF substrate for NADH and silver was the optimal MEF substrate for flavins. This is because the plasmon resonance properties of aluminum lie in the UV-blue regime and that of silver lie in the visible region. We also present the results of single molecule studies on FMN which show SIFs can both significantly enhance the intrinsic emission from single FMN molecules, significantly reduce their lifetimes and also significantly reduce FMN blinking. This is the first report of the observation of MEF from cofactors both at the ensemble and single molecule level. We hope this study will serve as a platform to encourage the future use of metallic nanostructures to study cofactors using their intrinsic fluorescence to directly monitor enzyme binding reactions without the need of extrinsic labeling of the molecules.</p>","PeriodicalId":520808,"journal":{"name":"The journal of physical chemistry. C, Nanomaterials and interfaces","volume":" ","pages":"7298-7308"},"PeriodicalIF":0.0,"publicationDate":"2011-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3097113/pdf/nihms-284122.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40101102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing Gold Nanoparticle Cluster Configurations (n ≤ 7) for Array Applications.","authors":"Bo Yan, Svetlana V Boriskina, Björn M Reinhard","doi":"10.1021/jp112146d","DOIUrl":"10.1021/jp112146d","url":null,"abstract":"<p><p>Nanoparticle cluster arrays (NCAs) are novel electromagnetic materials whose properties depend on the size and shape of the constituent nanoparticle clusters. A rational design of NCAs with defined optical properties requires a thorough understanding of the geometry dependent optical response of the building blocks. Herein, we systematically investigate the near- and far-field responses of clusters of closely packed 60 nm gold nanoparticles (n ≤ 7) as a function of size and cluster geometry through a combination of experimental spectroscopy and generalized Mie Theory calculations. From all of the investigated cluster configurations, nanoparticle trimers with D(3h) geometry and heptamers in D(6h) geometry stand out due to their polarization insensitive responses and high electric (E-) field intensity enhancement, making them building blocks of choice in this size range. The near-field intensity maximum of the D(6h) heptamer is red-shifted with regard to the D(3h) trimer by 125 nm, which confirms the possibility of a rational tuning of the near-field response in NCAs through the choice of the constituent nanoparticle clusters. For the nanoparticle trimer we investigate the influence of the cluster geometry on the optical response in detail and map near- and far-field spectra associated with the transition of the cluster configuration from D(3h) into D(∞h).</p>","PeriodicalId":520808,"journal":{"name":"The journal of physical chemistry. C, Nanomaterials and interfaces","volume":" ","pages":"4578-4583"},"PeriodicalIF":0.0,"publicationDate":"2011-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3095971/pdf/nihms-277652.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40101150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}