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1.
Pure water which is free of toxic chemicals is necessary for human health. So, detection and control of heavy metal ions in water is very important. Keeping this in mind, selective and sensitive optical sensor based on surface plasmon resonance for detection of various heavy metals in water using gold nanoparticles was explained in this present study. These AuNPs were prepared using Hibiscus cannabinus leaf extract as reducing agent with the average particle size of 22 nm. These gold nanoparticles are considerably selective and sensitive towards Fe3+ and it was used to detect the concentration of Fe3+ ions in water in the range 29.82–173.74 μM by tracking the absorbance changes of SPR band and the sensitivity of the system towards the Fe3+ concentration and it was found to be 0.0037 μM?1. We hope that these gold nanoparticles can be used for detecting Fe3+ ions concentration, in the water purification processes. 相似文献
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Achamma Kurian C V Bindhu S S Harilal Riju C Issac V P N Nampoori C P G Vallabhan 《Pramana》1994,43(5):401-406
A simple method based on laser beam deflection to study the variation of diffusion coefficient with concentration in a solution
is presented. When a properly fanned out laser beam is passed through a rectangular cell filled with solution having concentration
gradient, the emergent beam traces out a curved pattern on a screen. By taking measurements on the pattern at different concentrations,
the variation of diffusion coefficient with concentration can be determined. 相似文献
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C V Bindhu S S Harilal Riju C Issac Geetha K Varier V P N Nampoori C P G Vallabhan 《Pramana》1995,44(3):231-235
Pulsed photoacoustic measurements have been carried out in toluene at 532 nm wavelength using a Q-switched frequency doubled
Nd:YAG laser. The variation of photoacoustic signal amplitude with incident laser power indicates that at lower laser powers
one photon absorption takes place at this wavelength while a clear two photon absorption occurs in this liquid at higher laser
powers. The studies made here demonstrate that pulsed photoacoustic technique is simple and effective for the investigation
of multiphoton processes in liquids. 相似文献
4.
Magnetic iron oxide nanoparticles for biorecognition: evaluation of surface coverage and activity 总被引:1,自引:0,他引:1
Koh I Wang X Varughese B Isaacs L Ehrman SH English DS 《The journal of physical chemistry. B》2006,110(4):1553-1558
Modifying the surfaces of magnetic nanoparticles (MNPs) by the covalent attachment of biomolecules will enable their implementation as contrast agents for magnetic resonance imaging or as media for magnetically assisted bioseparations. In this paper we report both the surface coverage and the activity of IgG antibodies on MNPs. The antibodies were immobilized on gamma-Fe2O3 nanoparticles by conventional methods using aminopropyltriethoxy silane and subsequent activation by glutaraldehyde. Novel fluorescence methods were used to provide a quantitative evaluation of this well-known approach. Our results show that surface coverage can be stoichiometrically adjusted with saturated surface coverage occurring at approximately 36% of the theoretical limit. The saturated surface coverage corresponds to 34 antibody molecules bound to an average-sized MNP (32 nm diameter). We also show that the immobilized antibodies retain approximately 50% of their binding capacity at surface-saturated levels. 相似文献
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Time resolved optical emission spectroscopy is employed to study the expansion dynamics of C2 species in a graphite plasma produced during the Nd : YAG ablation. At low laser fluences a single peak distribution with
low kinetic energy is observed. At higher fluences a twin peak distribution is found. It has been noted that these double
peak time of flight distribution splits into a triple peak structure at distances ≥17mm from the target surface. The reason
for the occurrence of multiple peak is due to different formation mechanisms of C2 species. 相似文献
6.
S.S. Harilal C.V. Bindhu V.P.N. Nampoori C.P.G. Vallabhan 《Applied physics. B, Lasers and optics》1998,66(5):633-638
2 Cu3O7 target in vacuum and the plasma thus generated was studied using time-resolved spectroscopic techniques. Line broadening
of the Ba I emission line at 553.5 nm was monitored as a function of time elapsed after the incidence of a laser pulse on
the target. Measured line profiles of barium species were used to infer the electron density and temperature, and the time
evolution of these important plasma parameters has been worked out.
Received: 23 April 1997/Revised version: 25 August 1997 相似文献
7.
C V Bindhu S S Harilal Riju C Issac Geetha K Varier V P N Nampoori C P G Vallabhan 《Pramana》1995,44(3):225-229
Thermal lens signals in solutions of rhodamine B laser dye in methanol are measured using the dual beam pump-probe technique.
The nature of variations of signal strength with concentration is found to be different for 514 and 488 nm Ar+ laser excitations. However, both the pump wavelengths produce an oscillatory type variation of thermal lens signal amplitude
with the concentration of the dye solution. Probable reasons for this peculiar behaviour (which is absent in the case of fluorescent
intensity) are mentioned. 相似文献
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