101
|
Voznyy O, Dubowski JJ. c(4x2) structures of alkanethiol monolayers on Au (111) compatible with the constraint of dense packing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:7353-7358. [PMID: 19466814 DOI: 10.1021/la8043347] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Using alkanethiol dense packing as a starting point, we have found six prototypical packing structures commensurate with the (3x2 radical3) supercell of the Au (111) surface. Five of the six structures are not compatible with the flat surface conditions but can be fitted to a reconstructed surface. Combined with density functional theory calculations and simulations of grazing incidence X-ray diffraction maps and of scanning tunneling microscopy images, this allowed us to refine and assess the recently proposed models of the c(4x2) self-assembled monolayers involving thiolate-adatom and thiolate-adatom-thiolate species and to propose a new model with four gold adatoms per unit cell.
Collapse
Affiliation(s)
- Oleksandr Voznyy
- Department of Electrical and Computer Engineering, Centre of Excellence for Information Engineering (CEGI), Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada.
| | | |
Collapse
|
102
|
Lee K, Nair PR, Scott A, Alam MA, Janes DB. Device considerations for development of conductance-based biosensors. JOURNAL OF APPLIED PHYSICS 2009; 105:102046. [PMID: 24753627 PMCID: PMC3982583 DOI: 10.1063/1.3116630] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 01/05/2009] [Indexed: 05/19/2023]
Abstract
Design and fabrication of electronic biosensors based on field-effect-transistor (FET) devices require understanding of interactions between semiconductor surfaces and organic biomolecules. From this perspective, we review practical considerations for electronic biosensors with emphasis on molecular passivation effects on FET device characteristics upon immobilization of organic molecules and an electrostatic model for FET-based biosensors.
Collapse
|
103
|
Goykhman I, Korbakov N, Bartic C, Borghs G, Spira ME, Shappir J, Yitzchaik S. Direct Detection of Molecular Biorecognition by Dipole Sensing Mechanism. J Am Chem Soc 2009; 131:4788-94. [DOI: 10.1021/ja809051p] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ilya Goykhman
- Institute of Chemistry, School of Engineering, Department of Neurobiology, The Hebrew University of Jerusalem, Safra Campus - Givat Ram, 91904, Jerusalem, Israel, and IMEC, MCP/ART, Cell Based Sensors & Circuits, Kapeldreef 75, 3001 Heverlee, Belgium
| | - Nina Korbakov
- Institute of Chemistry, School of Engineering, Department of Neurobiology, The Hebrew University of Jerusalem, Safra Campus - Givat Ram, 91904, Jerusalem, Israel, and IMEC, MCP/ART, Cell Based Sensors & Circuits, Kapeldreef 75, 3001 Heverlee, Belgium
| | - Carmen Bartic
- Institute of Chemistry, School of Engineering, Department of Neurobiology, The Hebrew University of Jerusalem, Safra Campus - Givat Ram, 91904, Jerusalem, Israel, and IMEC, MCP/ART, Cell Based Sensors & Circuits, Kapeldreef 75, 3001 Heverlee, Belgium
| | - Gustaaf Borghs
- Institute of Chemistry, School of Engineering, Department of Neurobiology, The Hebrew University of Jerusalem, Safra Campus - Givat Ram, 91904, Jerusalem, Israel, and IMEC, MCP/ART, Cell Based Sensors & Circuits, Kapeldreef 75, 3001 Heverlee, Belgium
| | - Micha E. Spira
- Institute of Chemistry, School of Engineering, Department of Neurobiology, The Hebrew University of Jerusalem, Safra Campus - Givat Ram, 91904, Jerusalem, Israel, and IMEC, MCP/ART, Cell Based Sensors & Circuits, Kapeldreef 75, 3001 Heverlee, Belgium
| | - Joseph Shappir
- Institute of Chemistry, School of Engineering, Department of Neurobiology, The Hebrew University of Jerusalem, Safra Campus - Givat Ram, 91904, Jerusalem, Israel, and IMEC, MCP/ART, Cell Based Sensors & Circuits, Kapeldreef 75, 3001 Heverlee, Belgium
| | - Shlomo Yitzchaik
- Institute of Chemistry, School of Engineering, Department of Neurobiology, The Hebrew University of Jerusalem, Safra Campus - Givat Ram, 91904, Jerusalem, Israel, and IMEC, MCP/ART, Cell Based Sensors & Circuits, Kapeldreef 75, 3001 Heverlee, Belgium
| |
Collapse
|
104
|
Han X, Kuang Q, Jin M, Xie Z, Zheng L. Synthesis of Titania Nanosheets with a High Percentage of Exposed (001) Facets and Related Photocatalytic Properties. J Am Chem Soc 2009; 131:3152-3. [DOI: 10.1021/ja8092373] [Citation(s) in RCA: 1396] [Impact Index Per Article: 93.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiguang Han
- State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Qin Kuang
- State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Mingshang Jin
- State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Zhaoxiong Xie
- State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Lansun Zheng
- State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| |
Collapse
|
105
|
Zhang D, Li G, Yang X, Yu JC. A micrometer-size TiO2 single-crystal photocatalyst with remarkable 80% level of reactive facets. Chem Commun (Camb) 2009:4381-3. [DOI: 10.1039/b907963g] [Citation(s) in RCA: 321] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
106
|
Suzuki T, Lutz T, Payer D, Lin N, Tait SL, Costantini G, Kern K. Substrate effect on supramolecular self-assembly: from semiconductors to metals. Phys Chem Chem Phys 2009; 11:6498-504. [DOI: 10.1039/b905125b] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
107
|
Hilner E, Håkanson U, Fröberg LE, Karlsson M, Kratzer P, Lundgren E, Samuelson L, Mikkelsen A. Direct atomic scale imaging of III-V nanowire surfaces. NANO LETTERS 2008; 8:3978-3982. [PMID: 18850752 DOI: 10.1021/nl802500d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We have succeeded in direct atomic scale imaging of the exterior surfaces of III-V nanowires by scanning tunneling microscopy (STM). By using atomic hydrogen, we expose the crystalline surfaces of InAs nanowires with regular InP segments in vacuum while retaining the wire morphology. We show images with atomic resolution of the two major types of InAs wurtzite nanowire surface facets and scanning tunneling spectroscopy (STS) data. Ab initio calculations of the lowest energy surface structures and simulated STM images, agree very well with experiments.
Collapse
Affiliation(s)
- Emelie Hilner
- Department of Physics, Lund University, Box 118, 22100 Lund, Sweden
| | | | | | | | | | | | | | | |
Collapse
|
108
|
Zhang YH, Zhang HS, Guo XF, Wang H. L-Cysteine-coated CdSe/CdS core-shell quantum dots as selective fluorescence probe for copper(II) determination. Microchem J 2008. [DOI: 10.1016/j.microc.2008.01.008] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
109
|
Forniés J, Fuertes S, López JA, Martín A, Sicilia V. New Water Soluble and Luminescent Platinum(II) Compounds, Vapochromic Behavior of [K(H2O)][Pt(bzq)(CN)2], New Examples of the Influence of the Counterion on the Photophysical Properties of d8 Square-Planar Complexes. Inorg Chem 2008; 47:7166-76. [DOI: 10.1021/ic800265q] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Juan Forniés
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, Universidad de Zaragoza—CSIC, Plaza S. Francisco s/n 50009 Zaragoza, Spain, and Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Escuela Universitaria de Ingeniería Técnica Industrial, Universidad de Zaragoza—CSIC, Campus Universitario del Actur, Edificio Torres Quevedo, 50018, Zaragoza, Spain
| | - Sara Fuertes
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, Universidad de Zaragoza—CSIC, Plaza S. Francisco s/n 50009 Zaragoza, Spain, and Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Escuela Universitaria de Ingeniería Técnica Industrial, Universidad de Zaragoza—CSIC, Campus Universitario del Actur, Edificio Torres Quevedo, 50018, Zaragoza, Spain
| | - J. Antonio López
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, Universidad de Zaragoza—CSIC, Plaza S. Francisco s/n 50009 Zaragoza, Spain, and Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Escuela Universitaria de Ingeniería Técnica Industrial, Universidad de Zaragoza—CSIC, Campus Universitario del Actur, Edificio Torres Quevedo, 50018, Zaragoza, Spain
| | - Antonio Martín
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, Universidad de Zaragoza—CSIC, Plaza S. Francisco s/n 50009 Zaragoza, Spain, and Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Escuela Universitaria de Ingeniería Técnica Industrial, Universidad de Zaragoza—CSIC, Campus Universitario del Actur, Edificio Torres Quevedo, 50018, Zaragoza, Spain
| | - Violeta Sicilia
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, Universidad de Zaragoza—CSIC, Plaza S. Francisco s/n 50009 Zaragoza, Spain, and Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Escuela Universitaria de Ingeniería Técnica Industrial, Universidad de Zaragoza—CSIC, Campus Universitario del Actur, Edificio Torres Quevedo, 50018, Zaragoza, Spain
| |
Collapse
|
110
|
Shi GH, Shang ZB, Wang Y, Jin WJ, Zhang TC. Fluorescence quenching of CdSe quantum dots by nitroaromatic explosives and their relative compounds. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 70:247-52. [PMID: 17870656 DOI: 10.1016/j.saa.2007.07.054] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Revised: 07/12/2007] [Accepted: 07/24/2007] [Indexed: 05/17/2023]
Abstract
CdSe quantum dots (QDs) were synthesized in oleic acid and octadecene medium under high-temperature and dispersed in chloroform. Nitroaromatic explosives and their relative compounds, 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), nitrobenzene (NB), 2,4-dinitrochlorobenzene (DNBCl) and p-nitrotoluene (NT) can obviously cause the fluorescence quenching of the synthesized QDs. Under the optimum conditions, a nonlinear response was observed over the concentration range of 10(-8) to 10(-5) M for them all. The modified Stern-Volmer quenching equations of ln I(0)/I versus C show a good linear relation in 10(-5) M order of magnitude, and the detection limits approach 10(-6) to 10(-7) M.
Collapse
Affiliation(s)
- Guo Hua Shi
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | | | | | | | | |
Collapse
|
111
|
Interaction of water-soluble thiol capped CdTe quantum dots and bovine serum albumin. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2008.02.008] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
112
|
Peor N, Sfez R, Yitzchaik S. Variable density effect of self-assembled polarizable monolayers on the electronic properties of silicon. J Am Chem Soc 2008; 130:4158-65. [PMID: 18314981 DOI: 10.1021/ja077933g] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electronic structures at the Si/SiO2/molecule interfaces were studied by Kelvin probe techniques (contact potential difference) and compared to theoretical values derived by the Helmholtz equation. Two parameters influencing the electronic properties of n-type <100> Si/SiO2 substrates were systematically tuned: the molecular dipole of coupling agent molecules comprising the layer and the surface coverage of the chromophoric layer. The first parameter was checked using direct covalent grafting of a series of trichlorosilane-containing coupling agent molecules with various end groups causing a different dipole with the same surface number density. It was found that the change in band bending (DeltaBB) clearly indicated a major effect of passivation due to two-dimensional polysiloxane network formation, with minor differences resulting from the differences in the end groups' capacity to act as "electron traps". The change in electron affinity (DeltaEA) parameter increased upon increasing the dipole of the end group comprising the monolayer, resulting in a range of 600 mV. Moreover, a shielding effect of the aromatic spacer compared with the aliphatic spacer was found and estimated to be about 200 mV. The density effect was examined using the 4-[4-(N,N-dimethylamino phenyl)azo]pyridinium halide chromophore which has a calculated dipole of more than 10 D. It was clearly shown that upon increasing surface chromophoric coverage an increase in the electronic effects on the Si substrate was observed. However, a major consequence of depolarization was also detected while comparing the experimental and calculated values.
Collapse
Affiliation(s)
- Naama Peor
- The Institute of Chemistry and the Hebrew University Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | | | | |
Collapse
|
113
|
Easily prepared high-quantum-yield CdS quantum dots in water using hyperbranched polyethylenimine as modifier. J Colloid Interface Sci 2008; 319:353-6. [DOI: 10.1016/j.jcis.2007.10.027] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 09/13/2007] [Accepted: 10/16/2007] [Indexed: 11/18/2022]
|
114
|
Potyrailo RA, Mirsky VM. Combinatorial and High-Throughput Development of Sensing Materials: The First 10 Years. Chem Rev 2008; 108:770-813. [DOI: 10.1021/cr068127f] [Citation(s) in RCA: 214] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
115
|
McGuiness CL, Blasini D, Masejewski JP, Uppili S, Cabarcos OM, Smilgies D, Allara DL. Molecular self-assembly at bare semiconductor surfaces: characterization of a homologous series of n-alkanethiolate monolayers on GaAs(001). ACS NANO 2007; 1:30-49. [PMID: 19203128 DOI: 10.1021/nn7000596] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Structural trends for a homologous series of n-alkanethiolate self-assembled monolayers (SAMs), C(n)H(2n+1)S- with 12 < or = n < or = 19, on GaAs(001), studied by a combination of grazing incidence X-ray diffraction and infrared spectroscopy, along with ancillary probes, show an overall decay in organization with decreasing n, with the largest changes occurring below n = 15-16. The long-chain monolayers form a mosaic structure with < or =10 nm domains of molecules organized in an incommensurate pseudo-hcp arrangement with nearest neighbor distances of 4.70 and 5.02 A, a 21.2 A(2) area per chain, two chains per subcell in a herringbone packing with a chain tilt angle of 14 degrees , and preferential domain alignment along the substrate [110]([110]) step edge direction. In contrast, for n < 14 no evidence of translational ordering is seen and the alkyl chains exhibit a loss of conformational ordering and coverage relative to the n > 16 cases. A 4'-methyl-biphenyl-4-thiolate companion SAM shows evidence for ordered structures but with lattice parameters close to those expected for a structure commensurate with the intrinsic GaAs(001) square lattice. These trends are explained on the basis of competitions between lattice, interfacial, and intermolecular forces controlling the nanoscale structures of the SAMs. Overall these results provide an important aspect of understanding the effects of SAM formation on surface properties such as electronic and chemical passivation.
Collapse
Affiliation(s)
- Christine L McGuiness
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16801-6300, USA
| | | | | | | | | | | | | |
Collapse
|
116
|
Gaweda S, Stochel G, Szaciłowski K. Bioinspired Nanodevice Based on the Folic Acid/Titanium Dioxide System. Chem Asian J 2007; 2:580-90. [PMID: 17465404 DOI: 10.1002/asia.200700025] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A new bioinspired nanomaterial has been obtained by chemisorption of folic acid onto nanocrystalline titanium dioxide. The organic chromophore is linked with the semiconductor surface via the glutamate chain and anchored with the carboxylate group. The geometry and electronic structure of the chromophore was studied in detail with DFT. Photoelectrochemical studies revealed photosensitization of the new material towards visible light. The photoelectrodes composed of the folic acid/titanium dioxide hybrid material generated photocurrent over a 300-600-nm window. Moreover, the direction of the photocurrent could be changed from anodic to cathodic and vice versa by application of the appropriate photoelectrode potential. Photoelectrochemical and spectroscopic studies allowed the elucidation of the mechanism of photocurrent switching. Photoelectrodes composed of folate-modified titanium dioxide may serve as a simple model of optoelectronic switches and may constitute the basis for molecular photoelectronic devices.
Collapse
Affiliation(s)
- Sylwia Gaweda
- Centrum Nanochemii Nieorganicznej, Wydział Chemii, Uniwersytet Jagielloński ul. Romana Ingardena 3, 30-060 Kraków, Poland
| | | | | |
Collapse
|
117
|
Theoretical modeling of the benzoic acid adsorption on the GaAs (001)-β2(2 × 4) oxidized surface. Theor Chem Acc 2007. [DOI: 10.1007/s00214-006-0230-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
118
|
Nesher G, Shpaisman H, Cahen D. Effect of Chemical Bond Type on Electron Transport in GaAs−Chemical Bond−Alkyl/Hg Junctions. J Am Chem Soc 2007; 129:734-5. [PMID: 17243789 DOI: 10.1021/ja065399r] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Guy Nesher
- Weizmann Institute of Science, Rehovoth 76100, Israel
| | | | | |
Collapse
|
119
|
Szaciłowski K, Macyk W, Hebda M, Stochel G. Redox-Controlled Photosensitization of Nanocrystalline Titanium Dioxide. Chemphyschem 2006; 7:2384-91. [PMID: 17029326 DOI: 10.1002/cphc.200600407] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Photosensitization of nanocrystalline titanium dioxide materials has been achieved by chemisorption of the pentacyanothiamineferrate(II) complex, which offers a relatively high redox potential that determines the photoelectrochemical properties of the photosensitized TiO(2). The adsorbed pentacyanoferrate complex binds to TiO(2) through the cyanide bridge and forms a new surface complex characterized by a metal-to-metal charge-transfer transition (MMCT) (Fe(II)-->Ti(IV)). The photosensitization can be observed only at low potentials at which Fe(II) moieties are present. Photocurrent switching between anodic and cathodic can be induced by varying either the photoelectrode potential or the wavelength of the incident light. Simple molecular modeling-together with spectroscopic and electrochemical measurements-allows the elucidation of the mechanism of the observed photoelectrochemical behavior.
Collapse
Affiliation(s)
- Konrad Szaciłowski
- Uniwersytet Jagielloński, Wydział Chemii ul. Romana Ingardena 3, 30-060 Kraków, Poland.
| | | | | | | |
Collapse
|
120
|
Voznyy O, Dubowski JJ. Structure, Bonding Nature, and Binding Energy of Alkanethiolate on As-Rich GaAs (001) Surface: A Density Functional Theory Study. J Phys Chem B 2006; 110:23619-22. [PMID: 17125316 DOI: 10.1021/jp064675l] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Chemisorption of alkanethiols on As-rich GaAs (001) surface under a low coverage condition was studied using first principles density functional calculations in a periodic supercell approach. The thiolate adsorption site, tilt angle and its direction are dictated by the high directionality of As dangling bond and sulfur 3p orbital participating in bonding and steric repulsion of the first three CH2 units from the surface. Small charge transfer between thiolate and surface, strong dependence of total energy on tilt angle, and a relatively short length of 2.28 A of the S-As bond indicate the highly covalent nature of the bonding. Calculated binding energy of 2.1 eV is consistent with the available experimental data.
Collapse
|
121
|
Chattopadhyay S, Bohn PW. Surfactant-Induced Modulation of Light Emission in Porous Silicon Produced by Metal-Assisted Electroless Etching. Anal Chem 2006; 78:6058-64. [PMID: 16944884 DOI: 10.1021/ac060411j] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoluminescent porous silicon (PSi) was produced by Pt-assisted electroless chemical etching of p(-)-Si in a 1:1:2 (v/v/v) solution of HF, methanol, and H2O2. Upon irradiation with ultraviolet light PSi produced under these conditions luminesces with a peak emission near 590 nm that is sufficiently intense to be visible by eye. Because PSi light emission is an attractive modality for chemical sensing, the effect of charged surfactant adsorbates on the photoluminescence (PL) intensity was investigated. PSi was exposed to aqueous solutions of cationic, cetyltrimethylammonium bromide (CTAB), and anionic, sodium dodecyl sulfate (SDS), surfactants as a function of solution concentration and pH. Adsorption produces both chemical and physical changes at the PSi-solution interface, which were followed by a combination of PL and infrared absorption spectroscopy. Luminescence is quenched in the presence of CTAB and enhanced in the presence of SDS, both in a pH-dependent manner, the behavior being explained by a depletion layer model. PSi crystallites generated from p-Si exhibit a hole-depletion layer at the Si-solution interface, and the depletion layer expands in the presence of cationic surfactant and contracts in the presence of anionic surfactant. Because the surface depletion region is nonemissive (dead layer), surfactant adsorbate-induced modulation of the depletion layer width determines the luminescence intensity of PSi. At very basic pH, PL quenching was observed independent of surfactant identity or concentration, an observation likely tied to the dissolution of the PSi nanocrystallites in strong base.
Collapse
Affiliation(s)
- Soma Chattopadhyay
- Department of Chemistry, Beckman Institute for Advanced Sciences and Technology, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | | |
Collapse
|
122
|
Nesher G, Vilan A, Cohen H, Cahen D, Amy F, Chan C, Hwang J, Kahn A. Energy Level and Band Alignment for GaAs−Alkylthiol Monolayer−Hg Junctions from Electrical Transport and Photoemission Experiments. J Phys Chem B 2006; 110:14363-71. [PMID: 16854143 DOI: 10.1021/jp062181i] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of p- and n-GaAs-S-C(n)H(2n+1) || Hg junctions are prepared, and the electronic transport through them is measured. From current-voltage measurements, we find that, for n-GaAs, transport occurs by both thermionic emission and tunneling, with the former dominating at low forward bias and the latter dominating at higher forward bias. For p-GaAs, tunneling dominates at all bias voltages. By combining the analysis of the transport data with results from direct and inverse photoemission spectroscopy, we deduce an energy band diagram of the system, including the tunnel barrier and, with this barrier and within the Simmons tunneling model, extract an effective mass value of 1.5-1.6m(e) for the electronic carriers that cross the junctions. We find that transport is well-described by lowest unoccupied and highest occupied states at 1.3-1.4 eV above and 2.0-2.2 eV below the Fermi level. At the same time, the photoemission data indicate that there are continua of states from the conduction band minimum and the valence band maximum, the density of which varies with energy. On the basis of our results, it appears likely that, for both types of junctions, electrons are the main carrier type, although holes may contribute significantly to the transport in the p-GaAs system.
Collapse
Affiliation(s)
- Guy Nesher
- Weizmann Institute of Science, Rehovoth, Israel
| | | | | | | | | | | | | | | |
Collapse
|
123
|
Hebda M, Stochel G, Szaciłowski K, Macyk W. Optoelectronic Switches Based on Wide Band Gap Semiconductors. J Phys Chem B 2006; 110:15275-83. [PMID: 16884245 DOI: 10.1021/jp061262b] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Switching of photocurrent direction in semiconducting systems upon changes of the electrode potential or incident light wavelength was realized by a series of photoelectrodes covered with titania modified with pentacyanoferrate complexes, [Fe(CN)(5)L](n)(-) (L = NH(3), thiodiethanol, thiodipropanol). These materials were characterized by optical spectroscopy and electrochemistry. The structure of the surface complexes was modeled using simple quantum-chemical models. The electrodes described in this paper enable control of the photocurrent direction by two stimuli: Changing the wavelength or the photoelectrode potential easily switches the direction of photocurrent. The materials are different from those of similar characteristics studied by other authors: They are not composites comprising of two types of semiconductors but rather engineered uniform materials. The photocurrent switching phenomenon is an intrinsic feature resulting from a specific electronic structure of the surface-modified semiconductor.
Collapse
Affiliation(s)
- Maciej Hebda
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
| | | | | | | |
Collapse
|
124
|
Haick H, Ambrico M, Ligonzo T, Tung RT, Cahen D. Controlling Semiconductor/Metal Junction Barriers by Incomplete, Nonideal Molecular Monolayers. J Am Chem Soc 2006; 128:6854-69. [PMID: 16719466 DOI: 10.1021/ja058224a] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We study how partial monolayers of molecular dipoles at semiconductor/metal interfaces can affect electrical transport across these interfaces, using a series of molecules with systematically varying dipole moment, adsorbed on n-GaAs, prior to Au or Pd metal contact deposition, by indirect evaporation or as "ready-made" pads. From analyses of the molecularly modified surfaces, we find that molecular coverage is poorer on low- than on high-doped n-GaAs. Electrical charge transport across the resulting interfaces was studied by current-voltage-temperature, internal photoemission, and capacitance-voltage measurements. The data were analyzed and compared with numerical simulations of interfaces that present inhomogeneous barriers for electron transport across them. For high-doped GaAs, we confirm that only the former, molecular dipole-dependent barrier is found. Although no clear molecular effects appear to exist with low-doped n-GaAs, those data are well explained by two coexisting barriers for electron transport, one with clear systematic dependence on molecular dipole (molecule-controlled regions) and a constant one (molecule-free regions, pinholes). This explains why directly observable molecular control over the barrier height is found with high-doped GaAs: there, the monolayer pinholes are small enough for their electronic effect not to be felt (they are "pinched off"). We conclude that molecules can control and tailor electronic devices need not form high-quality monolayers, bind chemically to both electrodes, or form multilayers to achieve complete surface coverage. Furthermore, the problem of stability during electron transport is significantly alleviated with molecular control via partial molecule coverage, as most current flows now between, rather than via, the molecules.
Collapse
Affiliation(s)
- Hossam Haick
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | | | | | | |
Collapse
|
125
|
McGuiness CL, Shaporenko A, Mars CK, Uppili S, Zharnikov M, Allara DL. Molecular Self-Assembly at Bare Semiconductor Surfaces: Preparation and Characterization of Highly Organized Octadecanethiolate Monolayers on GaAs(001). J Am Chem Soc 2006; 128:5231-43. [PMID: 16608359 DOI: 10.1021/ja058657d] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Through rigorous control of preparation conditions, organized monolayers with a highly reproducible structure can be formed by solution self-assembly of octadecanethiol on GaAs (001) at ambient temperature. A combination of characterization probes reveal a structure with conformationally ordered alkyl chains tilted on average at 14 +/- 1 degrees from the surface normal with a 43 +/- 5 degrees twist, a highly oleophobic and hydrophobic ambient surface, and direct S-GaAs attachment. Analysis of the tilt angle and film thickness data shows a significant mismatch of the average adsorbate molecule spacings with the spacings of an intrinsic GaAs(001) surface lattice. The monolayers are stable up to approximately 100 degrees C and exhibit an overall thermal stability which is lower than that of the same monolayers on Au[111] surfaces. A two-step solution assembly process is observed: rapid adsorption of molecules over the first several hours to form disordered structures with molecules lying close to the substrate surface, followed by a slow densification and asymptotic approach to final ordering. This process, while similar to the assembly of alkanethiols on Au[111], is nearly 2 orders of magnitude slower. Finally, despite differences in assembly rates and the thermal stability, exchange experiments with isotopically tagged molecules show that the octadecanethiol on GaAs(001) monolayers undergo exchange with solute thiol molecules at roughly the same rate as the corresponding exchanges of the same monolayers on Au[111].
Collapse
Affiliation(s)
- Christine L McGuiness
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16801-6300, USA
| | | | | | | | | | | |
Collapse
|
126
|
|
127
|
Gattás-Asfura KM, Constantine CA, Lynn MJ, Thimann DA, Ji X, Leblanc RM. Characterization and 2D Self-Assembly of CdSe Quantum Dots at the Air−Water Interface. J Am Chem Soc 2005; 127:14640-6. [PMID: 16231916 DOI: 10.1021/ja0514848] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Langmuir film properties, UV-vis spectroscopy, epifluorescence microscopy, and transmission electron microscopy were used to study CdSe quantum dots (QDs) in 2D. By combining these results, it was possible to determine the molar absorptivity, limiting nanoparticle area, luminescence property, and arrangement of the QDs in the monolayer films at the air-water interface. Either trioctylphosphine oxide (TOPO) or 1-octadecanethiol (ODT) stabilized the QDs. The data collected reveal that TOPO forms close-packed monolayers on the surface of the QDs and that ODT-stabilized QDs undergo alkyl chains interdigitation. It was also found that varying the nanoparticle size, nature of surfactant, surface pressure, and mixed monolayers could help engineer the 2D self-assembly of the QDs at the air-water interface. Of practical importance is the transfer of these monolayer films onto hydrophilic or hydrophobic solid substrates, which could be successfully accomplished via the Langmuir-Blodgett film deposition technique.
Collapse
|
128
|
Liang JG, Zhang SS, Ai XP, Ji XH, He ZK. The interaction between some diamines and CdSe quantum dots. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 61:2974-8. [PMID: 16165039 DOI: 10.1016/j.saa.2004.11.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 11/05/2004] [Accepted: 11/08/2004] [Indexed: 05/04/2023]
Abstract
The interaction of some diamines (ethylenediamine (EDA), 1,6-hexanediamine (HDA), o-phenylenediamine (OPD)) with CdSe quantum dots (QDs) is reported. With increasing concentration of EDA from 0 to 2.0 x 10(-6) mol l(-1), slight fluorescence enhancement is observed. However, the CdSe QDs fluorescence quenching is seen at relatively higher concentration of EDA. There is a red-shift of 0-7 nm in fluorescence emission spectra of CdSe QDs when the concentration of EDA is changed from 2.0 x 10(-6) to 8.0 x 10(-6) mol l(-1). The resonance light scattering (RLS) spectra of CdSe QDs have little change when the concentration of EDA is less than 5.0 x 10(-6) mol l(-1). It indicates there are little large particles formed in the solution. However, a significant increase of the RLS is observed in the 300-500 nm wavelength range after adding higher concentration than 5.0 x 10(-6) mol l(-1) EDA, which could be attributed to the large particles formed. The interaction between HDA and CdSe QDs is similar to that of EDA. However, with the OPD, it is found that the interaction is much different from those of EDA, HDA, and that the quenching, even at low concentration, is effective for CdSe QDs emission. The quenching phenomenon could be explained by a surface bound complexation equilibrium model.
Collapse
Affiliation(s)
- Jian-Gong Liang
- Department of Chemistry, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | | | | | | | | |
Collapse
|
129
|
Botelho do Rego AM, Ferraria AM, El Beghdadi J, Debontridder F, Brogueira P, Naaman R, Rei Vilar M. Adsorption of phenylphosphonic acid on GaAs (100) surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:8765-73. [PMID: 16142959 DOI: 10.1021/la050682+] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The adsorption of phenylphosphonic acid (PPA) on GaAs (100) surfaces from solutions in acetonitrile/water mixtures was studied using Fourier transform infrared spectroscopy in attenuated total reflection in multiple internal reflections (ATR/MIR), X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and atomic force microscopy (AFM). ATR/MIR in situ showed that the accumulation of PPA molecules near the GaAs surface increased with the water concentration in the solution. For water contents lower than 4%, ATR/MIR and XPS results are consistent with the formation of a low-density monolayer. A mechanism is proposed for H2O percentages lower than 4% involving the creation of interfacial bonds through a Brønsted acid-base reaction, which involves the surface hydroxyl groups most probably bound to Ga. It was found that the morphology of the final layer depended strongly on the water concentration in the adsorbing solution. For water concentrations equal to or higher than 5%, the amount of adsorbed molecules drastically increased and was accompanied by modifications in the infrared spectral region corresponding to P-O and P=O. This sudden change indicates a deprotonation of the acid. XPS studies revealed the presence of extra oxygen atoms as well as gallium species in the layer, leading to the conclusion that phosphonate and hydrogenophosphonate ions are present in the PPA layer intercalated with H3O+ and Ga3+ ions. This mechanism enables the formation of layers approximately 10 times thicker than those obtained with lower H2O percentages. HREELS indicated that the surface is composed of regions covered by PPA layers and uncovered regions, but the uncovered regions disappeared for water contents equal to or higher than 5%. XPS results are interpreted using a model consisting of a monolayer partially covering the surface and a thick layer. This model is consistent with AFM images revealing roughness on the order of 7 nm for the thick layer and 0.2-0.5 nm for the thin layer. Sonication proves to be an effective method for reducing layer thickness.
Collapse
Affiliation(s)
- A M Botelho do Rego
- Centro de Química Física Molecular and ICEMS, Departamento de Física, Instituto Superior Técnico, P-1049-001 Lisboa, Portugal.
| | | | | | | | | | | | | |
Collapse
|
130
|
Iozzi MF, Cossi M. Ab Initio Theoretical Study of Substituted Dicarboxylic Acids Adsorbed on GaAs Surfaces: Correlation between Microscopic Properties and Observed Electrical Behavior. J Phys Chem B 2005; 109:15383-90. [PMID: 16852951 DOI: 10.1021/jp052855+] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Five substituted tartaric acid derivatives are studied using density functional theory, both isolated and adsorbed onto an oxidized GaAs cluster, to model molecular layers on semiconductor surfaces. The structures, energies, and electronic properties are computed to clarify the interactions responsible for the electric behavior of the modified surfaces, used in semiconductor/metal junction devices. The chemical structure of the molecule/GaAs adducts is optimized ab initio and discussed for the first time. A strong binding scheme is found, providing useful insights about the microscopic structure of the molecular layer. A widely used model based on molecular dipole layers is discussed and verified, by computing the dipole moment for the isolated systems and estimating the charge separation in the adducts; moreover the molecular orbitals energies are analyzed and correlated to the experimental measures of the modified surface electron affinity.
Collapse
Affiliation(s)
- Maria Francesca Iozzi
- Dipartimento di Chimica, Università di Napoli Federico II, Complesso Monte S. Angelo, via Cintia, I-80126 Napoli, Italy
| | | |
Collapse
|
131
|
Cho Y, Ivanisevic A. Covalent Attachment of TAT Peptides and Thiolated Alkyl Molecules on GaAs Surfaces. J Phys Chem B 2005; 109:12731-7. [PMID: 16852577 DOI: 10.1021/jp0515737] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Four TAT peptide fragments were used to functionalize GaAs surfaces by adsorption from solution. In addition, two well-studied alkylthiols, mercaptohexadecanoic acid (MHA) and 1-octadecanethiol (ODT) were utilized as references to understand the structure of the TAT peptide monolayer on GaAs. The different sequences of TAT peptides were employed in recognition experiments where a synthetic RNA sequence was tested to verify the specific interaction with the TAT peptide. The modified GaAs surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS). AFM studies were used to compare the surface roughness before and after functionalization. XPS allowed us to characterize the chemical composition of the GaAs surface and conclude that the monolayers composed of different sequences of peptides have similar surface chemistries. Finally, FT-IRRAS experiments enabled us to deduce that the TAT peptide monolayers have a fairly ordered and densely packed alkyl chain structure. The recognition experiments showed preferred interaction of the RNA sequence toward peptides with high arginine content.
Collapse
Affiliation(s)
- Youngnam Cho
- Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | | |
Collapse
|
132
|
|
133
|
Cai QJ, Fu GD, Zhu FR, Kang E, Neoh K. GaAs–Polymer Hybrids Formed by Surface‐Initiated Atom‐Transfer Radical Polymerization of Methyl Methacrylate. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200461570] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Qin Jia Cai
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779‐1936
- Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602, Singapore
| | - Guo Dong Fu
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779‐1936
| | - Fu Rong Zhu
- Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602, Singapore
| | - En‐Tang Kang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779‐1936
| | - Koon‐Gee Neoh
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779‐1936
| |
Collapse
|
134
|
Cai QJ, Fu GD, Zhu FR, Kang ET, Neoh KG. GaAs–Polymer Hybrids Formed by Surface‐Initiated Atom‐Transfer Radical Polymerization of Methyl Methacrylate. Angew Chem Int Ed Engl 2005; 44:1104-1107. [PMID: 15643652 DOI: 10.1002/anie.200461570] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Qin Jia Cai
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779-1936
- Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602, Singapore
| | - Guo Dong Fu
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779-1936
| | - Fu Rong Zhu
- Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602, Singapore
| | - En-Tang Kang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779-1936
| | - Koon-Gee Neoh
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260, Singapore, Fax: (+65) 6779-1936
| |
Collapse
|
135
|
Petrovykh DY, Sullivan JM, Whitman LJ. Quantification of discrete oxide and sulfur layers on sulfur-passivated InAs by XPS. SURF INTERFACE ANAL 2005. [DOI: 10.1002/sia.2095] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
136
|
Debiemme-Chouvy C, Wartelle C, Sauvage FX. First Evidence of the Oxidation and Regeneration of Polysulfides at a GaAs Electrode, under Anodic Conditions. A Study by in Situ UV−Visible Spectroelectrochemistry. J Phys Chem B 2004. [DOI: 10.1021/jp046977y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
137
|
Hirakawa T, Kamat PV. Photoinduced electron storage and surface plasmon modulation in Ag@TiO2 clusters. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:5645-7. [PMID: 16459570 DOI: 10.1021/la048874c] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The reversible charging and discharging effects associated with photoexcitation of a TiO2 shell in a Ag@TiO2 composite are described. The photoinduced charge separation in the TiO2 shell is followed by electron injection into the silver core. Interestingly, the charging of the silver core is associated with the shift in the surface plasmon band from 460 to 430 nm. The stored electrons are discharged upon exposure of the charged Ag@/TiO2 composite to an electron acceptor. As the electrons from the silver core are discharged, the original surface plasmon absorption of the Ag core is restored.
Collapse
Affiliation(s)
- Tsutomu Hirakawa
- Notre Dame Radiation Laboratory and Department of Chemical & Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556-0579, USA
| | | |
Collapse
|
138
|
Javier A, Strouse GF. Activated and intermittent photoluminescence in thin CdSe quantum dot films. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.04.084] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
139
|
Obare SO, Meyer GJ. Nanostructured materials for environmental remediation of organic contaminants in water. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2004; 39:2549-2582. [PMID: 15509009 DOI: 10.1081/ese-200027010] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Nanostructured materials have opened new avenues in various scientific fields and are providing novel opportunities in environmental science. The increased surface area-to-volume ratio of nanoparticles, quantum size effects, and the ability to tune surface properties through molecular modification make nanostructures ideal for many environmental remediation applications. We describe herein the fabrication of metal and semiconductor nanoparticles for environmental remediation applications, particularly in ground water. We then summarize literature reports of nanostructures specifically tailored for remediation of environmental contaminants including organohalides, trinitrotoluene, and phenols.
Collapse
Affiliation(s)
- Sherine O Obare
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA
| | | |
Collapse
|
140
|
Stewart MP, Maya F, Kosynkin DV, Dirk SM, Stapleton JJ, McGuiness CL, Allara DL, Tour JM. Direct Covalent Grafting of Conjugated Molecules onto Si, GaAs, and Pd Surfaces from Aryldiazonium Salts. J Am Chem Soc 2003; 126:370-8. [PMID: 14709104 DOI: 10.1021/ja0383120] [Citation(s) in RCA: 290] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using aryldiazonium salts that are air-stable and easily synthesized, we describe here a one-step, room-temperature route to direct covalent bonds between pi-conjugated organic molecules on three material surfaces: Si, GaAs, and Pd. The Si can be in the form of single crystal Si including heavily doped p-type Si, intrinsic Si, heavily doped n-type Si, on Si(111) and Si(100), and on n-type polycrystalline Si. The formation of the aryl-metal or aryl-semiconductor bond attachments was confirmed by corroborating evidence from ellipsometry, reflectance FTIR, XPS, cyclic voltammetry, and AFM analyses of the surface-grafted monolayers. A data-encompassing explanation for the mechanism suggests a diazonium activation by reduction at the open circuit potential, with aryl radical secondary products bonding to the surface. The synthetic details are included for preparing the surface-grafted monolayers and the precursor diazonium salts. This spontaneous diazonium activation reaction offers an attractive route to highly passivating, robust monolayers and multilayers on many surfaces that allow for strong bonds between carbon and surface atoms with molecular species that are near perpendicular to the surface.
Collapse
Affiliation(s)
- Michael P Stewart
- Departments of Chemistry and Mechanical Engineering and Materials Science, and Center for Nanoscale Science and Technology, MS-222, Rice University, Houston, Texas 77005, USA
| | | | | | | | | | | | | | | |
Collapse
|
141
|
Sharma SN, Pillai ZS, Kamat PV. Photoinduced Charge Transfer between CdSe Quantum Dots and p-Phenylenediamine. J Phys Chem B 2003. [DOI: 10.1021/jp034109f] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Zeena S. Pillai
- Notre Dame Radiation Laboratory, Notre Dame, Indiana 46556-0579
| | | |
Collapse
|
142
|
Vilan A, Ghabboun J, Cahen D. Molecule−Metal Polarization at Rectifying GaAs Interfaces. J Phys Chem B 2003. [DOI: 10.1021/jp026779b] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ayelet Vilan
- Department of Materials & Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Jamal Ghabboun
- Department of Materials & Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100
| | - David Cahen
- Department of Materials & Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100
| |
Collapse
|
143
|
Gershevitz O, Sukenik CN, Ghabboun J, Cahen D. Molecular monolayer-mediated control over semiconductor surfaces: evidence for molecular depolarization of silane monolayers on Si/SiO(x). J Am Chem Soc 2003; 125:4730-1. [PMID: 12696890 DOI: 10.1021/ja029529h] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We show that, for molecules with particularly strong dipoles, their organization into a monomolecular layer can lead to depolarization, something that limits the range over which the substrate's work function can be changed. It appears that, with molecules, depolarization is achieved by changes in orientation and conformation, rather than by charge transfer to the substrate as is common for atomic layers.
Collapse
Affiliation(s)
- Olga Gershevitz
- Chemistry Department, Bar-Ilan University, Ramat Gan 52900, Israel
| | | | | | | |
Collapse
|
144
|
Adlkofer K, Eck W, Grunze M, Tanaka M. Surface Engineering of Gallium Arsenide with 4-Mercaptobiphenyl Monolayers. J Phys Chem B 2002. [DOI: 10.1021/jp0267813] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Klaus Adlkofer
- Lehrstuhl für Biophysik E22, Technische Universität München, James-Franck-Strasse, D-85748 Garching, Germany, and Lehrstuhl für Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Wolfgang Eck
- Lehrstuhl für Biophysik E22, Technische Universität München, James-Franck-Strasse, D-85748 Garching, Germany, and Lehrstuhl für Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Michael Grunze
- Lehrstuhl für Biophysik E22, Technische Universität München, James-Franck-Strasse, D-85748 Garching, Germany, and Lehrstuhl für Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Motomu Tanaka
- Lehrstuhl für Biophysik E22, Technische Universität München, James-Franck-Strasse, D-85748 Garching, Germany, and Lehrstuhl für Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| |
Collapse
|
145
|
Drew SM, Janzen DE, Mann KR. Characterization of a cross-reactive electronic nose with vapoluminescent array elements. Anal Chem 2002; 74:2547-55. [PMID: 12069236 DOI: 10.1021/ac011255d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A three-channel cross-reactive sensor array based on vapoluminescent platinum(II) double salt materials has been characterized. Two arrays were studied, one consisting of [Pt(CN-cyclododecyl)4][Pt(CN)4] (1), [(phen)Pt(CN-cyclohexyl)2][Pt(CN)4] (2), and [Pt(CN-n-tetradecyl)4][Pt-(CN)4] (3) materials, where phen = 1,10-phenanthroline, and a second array that has compound 3 replaced by the mixed double salt material [(phen)Pt(CN-cyclododecyl)Cl)]2[(phen)Pt(CN-cyclododecyl)2]2[Pt(CN)4]3 (4). Compounds 2, 3 and 4 are characterized here for the first time. Inclusion of solvent vapors into these materials often leads to dramatic shifts in their solid-state absorption and luminescence spectra. In these studies the arrays were exposed to a set of 10 test solvent vapors to determine the ability of each cross-reactive array to give reproducible vapoluminescent spectra characteristic of each solvent vapor. It was discovered that temperature programming between solvent vapor exposures greatly improved the reproducibility of the luminescence spectra obtained. A statistical analysis of three-dimensional resolution factors between pairs of solvent clusters in principal component space supported this assertion. The success of the temperature programming protocol was limited by the thermal stability and the sensitivity to low background water vapor levels of some platinum(II) double salt materials. The ability of the cross-reactive sensor array to differentiate between two different solvent vapors over a large concentration range was also investigated. Acetone and methanol were found to occupy two distinct regions of the three-dimensional principal component space. Detection limits for acetone and methanol were estimated from the principal component analysis as 75 and 6 g/m3, respectively.
Collapse
Affiliation(s)
- Steven M Drew
- Department of Chemistry, University of Minnesota, Minneapolis 55455, USA
| | | | | |
Collapse
|
146
|
Buss CE, Mann KR. Synthesis and characterization of Pt(CN-p-(C(2)H(5))C(6)H(4))(2)(CN)(2), a crystalline vapoluminescent compound that detects vapor-phase aromatic hydrocarbons. J Am Chem Soc 2002; 124:1031-9. [PMID: 11829612 DOI: 10.1021/ja011986v] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The vapochromic and vapoluminescent compound Pt(CN-p-(C(2)H(5))C(6)H(4))(2)(CN)(2) (abbreviated PtC(2)) is conveniently synthesized by the thermal rearrangement of [Pt(CN-p-(C(2)H(5))C(6)H(4))(4)][Pt(CN)(4)]. Recrystallization of PtC(2) gives a crystalline orange morph (O-PtC(2)) and an amorphous purple morph (P-PtC(2)) that both contain the cis isomer and differ only in their solid-state packing arrangements. Both compounds were fully characterized by elemental analysis, X-ray powder diffraction, NMR, IR, and TGA. O-PtC(2) is vapochromic and vapoluminescent: it reversibly sorbs aromatic hydrocarbons and ethanol from air or nitrogen with resulting color changes and shifts in the emission spectrum. The lambda(max) values (nm) for emission from O-PtC(2) x (guest) are as follows: no guest, 611; toluene, 565; benzene, 586; chlorobenzene, 592; p-xylene, 585; mesitylene, 565; ethanol, 587. In the case of toluene and mesitylene, intermediate emitting phases are observed. Recrystallization of O-PtC(2) from dichloromethane/toluene gave single crystals of PtC(2) x 0.5(toluene). The single-crystal X-ray structure of PtC(2) x 0.5(toluene) contains infinite stacks of cis geometry and planar molecules with chains of platinum atoms parallel to the c axis of the monoclinic unit cell. The average Pt-Pt separation in PtC(2) x 0.5(toluene) is c/4 = 3.288(2) A. There are solvent channels parallel with the c axis that contain the toluene molecule guests. Thin films of O-PtC(2) rapidly sorb toluene from the gas phase to form PtC(2) x 0.25(toluene) and PtC(2) x 0.5(toluene). Long-term exposure gives PtC(2) x 1.0(toluene). Removal of the toluene source causes rapid desorption to PtC(2) x 0.5(toluene) and then to PtC(2) x 0.25(toluene). The remaining 0.25(toluene) lattice guests require heating for rapid removal. X-ray powder diffraction identified the PtC(2),PtC(2) x .25(toluene), and PtC(2) x 0.5(toluene) phases and showed that the sorption of toluene is accompanied by small changes in the unit cell dimensions that include lengthening the Pt-Pt distances in the structure. The sorption process improves the packing in the structure by utilizing some of the free volume for the toluene lattice guests.
Collapse
Affiliation(s)
- Carrie E Buss
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | | |
Collapse
|
147
|
Ashkenasy G, Cahen D, Cohen R, Shanzer A, Vilan A. Molecular engineering of semiconductor surfaces and devices. Acc Chem Res 2002; 35:121-8. [PMID: 11851390 DOI: 10.1021/ar990047t] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Grafting organic molecules onto solid surfaces can transfer molecular properties to the solid. We describe how modifications of semiconductor or metal surfaces by molecules with systematically varying properties can lead to corresponding trends in the (electronic) properties of the resulting hybrid (molecule + solid) materials and devices made with them. Examples include molecule-controlled diodes and sensors, where the electrons need not to go through the molecules (action at a distance), suggesting a new approach to molecule-based electronics.
Collapse
|
148
|
Drew SM, Janzen DE, Buss CE, MacEwan DI, Dublin KM, Mann KR. An electronic nose transducer array of vapoluminescent platinum(II) double salts. J Am Chem Soc 2001; 123:8414-5. [PMID: 11516298 DOI: 10.1021/ja016010x] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- S M Drew
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, Minneapolis, MN 55455, USA
| | | | | | | | | | | |
Collapse
|
149
|
Cui Y, Wei Q, Park H, Lieber CM. Nanowire nanosensors for highly sensitive and selective detection of biological and chemical species. Science 2001; 293:1289-92. [PMID: 11509722 DOI: 10.1126/science.1062711] [Citation(s) in RCA: 2285] [Impact Index Per Article: 99.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Boron-doped silicon nanowires (SiNWs) were used to create highly sensitive, real-time electrically based sensors for biological and chemical species. Amine- and oxide-functionalized SiNWs exhibit pH-dependent conductance that was linear over a large dynamic range and could be understood in terms of the change in surface charge during protonation and deprotonation. Biotin-modified SiNWs were used to detect streptavidin down to at least a picomolar concentration range. In addition, antigen-functionalized SiNWs show reversible antibody binding and concentration-dependent detection in real time. Lastly, detection of the reversible binding of the metabolic indicator Ca2+ was demonstrated. The small size and capability of these semiconductor nanowires for sensitive, label-free, real-time detection of a wide range of chemical and biological species could be exploited in array-based screening and in vivo diagnostics.
Collapse
Affiliation(s)
- Y Cui
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Q Wei
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - H Park
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - C M Lieber
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 USA
| |
Collapse
|
150
|
Ivanisevic A, Yeh JY, Mawst L, Kuech TF, Ellis AB. Light-emitting diodes as chemical sensors. Nature 2001; 409:476. [PMID: 11206534 DOI: 10.1038/35054131] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A Ivanisevic
- Department of Chemistry, University of Wisconsin, Madison 53706, USA
| | | | | | | | | |
Collapse
|