Gold nanoparticles were assembled on gold substrates with the self-assembled monolayer(SAM) of p-minothiophenol(PATP). AFM measurements disclose that gold nanoparticles are scattered over the surface of the substrate ...Gold nanoparticles were assembled on gold substrates with the self-assembled monolayer(SAM) of p-minothiophenol(PATP). AFM measurements disclose that gold nanoparticles are scattered over the surface of the substrate with a submonolayer coverage. The Raman signal of the coupling layer, the SAM of PATP, can be well observed. Potential-dependent measurements were performed to study the chemical enhancement in SERS of such a system. Based on the supposition that the direction of charge transfer is from gold nanoparticles to PATP, it is deduced that Herzberg-Teller contribution has ruled in the SERS of such a system.展开更多
Self Assembled Monolayers(SAMs) of a series of mercapto contained azobenzene derivatives with the structure of C n H 2 n +1 AzoO(CH 2) m SH (where n =4,6,8,10,12; with m =3,5 respectively) were prepared and characteri...Self Assembled Monolayers(SAMs) of a series of mercapto contained azobenzene derivatives with the structure of C n H 2 n +1 AzoO(CH 2) m SH (where n =4,6,8,10,12; with m =3,5 respectively) were prepared and characterized.Wettability measurement of water on the SAMs demonstrates that molecular packing density in the monolayers increases while the alkyl chain in the molecules is lengthened. Both the n and m values have similar contribution to the wetting property of SAMs. The RA IR spectra reveal that the alkyl chains in the SAMs tilt away dramatically from the surface normal direction with the increase in their length. However, the orientation of azobenzene moiety is found to be influenced slightly by the alkyl chain length, which is due to the tenderness of the molecule.展开更多
The formation kinetics of the self-assembled monolayer (SAM) of an azobenzenealkanethiol,denoted as AzoC2SH on surface was studied using electrochemical techniques,and the monolayers prepared at different assembly tim...The formation kinetics of the self-assembled monolayer (SAM) of an azobenzenealkanethiol,denoted as AzoC2SH on surface was studied using electrochemical techniques,and the monolayers prepared at different assembly times and concentration were also investigated.A two-step adsorption kinetics has been confirmed:the fast adsorption process and the following long-term reorganization.The equilibrium constant(K)for the adsorptioon and the interaction factor between adsorbate-adsorbate molecules () were evaluated based on the Frumkin isotherm and determined to be (3. 17±0. 13)× 106 mol.L(-1) and -0.34±0.04, respectively The Gibbs free energy (G)of SAM was determined to be -(37. 07±0. 13)kJ.mol(-1)展开更多
A simple method for fabricating SERS-active substrate using Au nanoparticles is reported. HSCH2CH2NH2 was self-assembled on the Au/glass substrate, then nanoparticles of colloidal gold were bound to the surface. The S...A simple method for fabricating SERS-active substrate using Au nanoparticles is reported. HSCH2CH2NH2 was self-assembled on the Au/glass substrate, then nanoparticles of colloidal gold were bound to the surface. The SERS effect of such prepared substrate was studied by using BPE and an azobenzene thiol derivated compound and the SERS enhanced factor was found about 3×103.展开更多
Mutual coupling of surface electromagnetic wave between different silver particles onsilver island substrates is realized experimentally and its effect on surface enhanced infrared spec-troscopy is studied. Silvcr isl...Mutual coupling of surface electromagnetic wave between different silver particles onsilver island substrates is realized experimentally and its effect on surface enhanced infrared spec-troscopy is studied. Silvcr island substrates of different size and distribution of silver particleshave been prepared by the vacuum evaporation and rapid thermal annealing, and characterizedby atomic force microscopy (AFM) and UV-visiblc spectroscopy. The surface enhanced infraredspectra of 4-Octyl-4’-(3-carboxy-trimethylene -oxy)-azobenzene (referred as ABD) LB monolayerare studied on such silver island films. The results elucidates the important role of the coupling ofsurface electromagnetic wave between silver particles in surface enhanced infrared spectroscopy.展开更多
A polydiacetylene nanocrystalline film has been fabricated using surface evaporationmethod and observed by using Aurora 2000, TopoMetrix scanning near-field optical microscope(SNOM) system. The SNOM images of this fil...A polydiacetylene nanocrystalline film has been fabricated using surface evaporationmethod and observed by using Aurora 2000, TopoMetrix scanning near-field optical microscope(SNOM) system. The SNOM images of this film together with the standard testing Al sampleindicate that the resolution of the system is better than 80 nm 1/6 of the incident wavelength,488 nm. The possibility of SNOM data storage using thus fabricated film is also demonstrated.展开更多
A novel azobenzene SAM-LB composite film was fabricated by depositing LangmuirBlodgett monolayer of 4-octyl-4’ - (3-carboxy-trimethylene-oxy)-azobenzene (ABD) onto the cysteamine self-assembled monolayer(AET SAM) mod...A novel azobenzene SAM-LB composite film was fabricated by depositing LangmuirBlodgett monolayer of 4-octyl-4’ - (3-carboxy-trimethylene-oxy)-azobenzene (ABD) onto the cysteamine self-assembled monolayer(AET SAM) modified gold substrate. The film stability was greatly improved and the molecular aggregation was effectively prevented by the strong ionic bonding character on the SAM-LB interface, which was evidenced by both contact-angle titration, RA-FTIR and AFM. The reversible tran/cis isomerization and the clear-cut electrochemical response of cis-azobenzene were observed in the presence of highly organized molecular assemblies. This enable us to carry out a kinetic study of the cis-azobenzene in highly organized monolayers, by which a "more" reversible and unique pH dependent electron-transfer kinetic behavior of azobenzene was shown within the novel SAM-LB composite films.展开更多
文摘Gold nanoparticles were assembled on gold substrates with the self-assembled monolayer(SAM) of p-minothiophenol(PATP). AFM measurements disclose that gold nanoparticles are scattered over the surface of the substrate with a submonolayer coverage. The Raman signal of the coupling layer, the SAM of PATP, can be well observed. Potential-dependent measurements were performed to study the chemical enhancement in SERS of such a system. Based on the supposition that the direction of charge transfer is from gold nanoparticles to PATP, it is deduced that Herzberg-Teller contribution has ruled in the SERS of such a system.
文摘Self Assembled Monolayers(SAMs) of a series of mercapto contained azobenzene derivatives with the structure of C n H 2 n +1 AzoO(CH 2) m SH (where n =4,6,8,10,12; with m =3,5 respectively) were prepared and characterized.Wettability measurement of water on the SAMs demonstrates that molecular packing density in the monolayers increases while the alkyl chain in the molecules is lengthened. Both the n and m values have similar contribution to the wetting property of SAMs. The RA IR spectra reveal that the alkyl chains in the SAMs tilt away dramatically from the surface normal direction with the increase in their length. However, the orientation of azobenzene moiety is found to be influenced slightly by the alkyl chain length, which is due to the tenderness of the molecule.
文摘The formation kinetics of the self-assembled monolayer (SAM) of an azobenzenealkanethiol,denoted as AzoC2SH on surface was studied using electrochemical techniques,and the monolayers prepared at different assembly times and concentration were also investigated.A two-step adsorption kinetics has been confirmed:the fast adsorption process and the following long-term reorganization.The equilibrium constant(K)for the adsorptioon and the interaction factor between adsorbate-adsorbate molecules () were evaluated based on the Frumkin isotherm and determined to be (3. 17±0. 13)× 106 mol.L(-1) and -0.34±0.04, respectively The Gibbs free energy (G)of SAM was determined to be -(37. 07±0. 13)kJ.mol(-1)
文摘A simple method for fabricating SERS-active substrate using Au nanoparticles is reported. HSCH2CH2NH2 was self-assembled on the Au/glass substrate, then nanoparticles of colloidal gold were bound to the surface. The SERS effect of such prepared substrate was studied by using BPE and an azobenzene thiol derivated compound and the SERS enhanced factor was found about 3×103.
文摘Mutual coupling of surface electromagnetic wave between different silver particles onsilver island substrates is realized experimentally and its effect on surface enhanced infrared spec-troscopy is studied. Silvcr island substrates of different size and distribution of silver particleshave been prepared by the vacuum evaporation and rapid thermal annealing, and characterizedby atomic force microscopy (AFM) and UV-visiblc spectroscopy. The surface enhanced infraredspectra of 4-Octyl-4’-(3-carboxy-trimethylene -oxy)-azobenzene (referred as ABD) LB monolayerare studied on such silver island films. The results elucidates the important role of the coupling ofsurface electromagnetic wave between silver particles in surface enhanced infrared spectroscopy.
文摘A polydiacetylene nanocrystalline film has been fabricated using surface evaporationmethod and observed by using Aurora 2000, TopoMetrix scanning near-field optical microscope(SNOM) system. The SNOM images of this film together with the standard testing Al sampleindicate that the resolution of the system is better than 80 nm 1/6 of the incident wavelength,488 nm. The possibility of SNOM data storage using thus fabricated film is also demonstrated.
文摘A novel azobenzene SAM-LB composite film was fabricated by depositing LangmuirBlodgett monolayer of 4-octyl-4’ - (3-carboxy-trimethylene-oxy)-azobenzene (ABD) onto the cysteamine self-assembled monolayer(AET SAM) modified gold substrate. The film stability was greatly improved and the molecular aggregation was effectively prevented by the strong ionic bonding character on the SAM-LB interface, which was evidenced by both contact-angle titration, RA-FTIR and AFM. The reversible tran/cis isomerization and the clear-cut electrochemical response of cis-azobenzene were observed in the presence of highly organized molecular assemblies. This enable us to carry out a kinetic study of the cis-azobenzene in highly organized monolayers, by which a "more" reversible and unique pH dependent electron-transfer kinetic behavior of azobenzene was shown within the novel SAM-LB composite films.
