Spherical gold nanoparticles

Kuhn et al. observed the fluorescence enhancement and fluorescence decay rate of a single terrylene molecule when a spherical gold nanoparticle was approached to the... 

Fig. 6 Spherical gold nanoparticles formed by the reaction of the reducing agent, NaBH4 with HAuCU in the Isooctane/AOT (0.8 M)/Lecithin (0.4 M) system Wo 60...

Cao L, Liu Z, Zhu T (2006) Eormation Mechanisms of Non-Spherical Gold Nanoparticles During Seeding Growth Roles of Anion Adsorption and Reduction Rate. J Colloid Interface Sci 293 67-69... 

Fig. 12 Optical near-field intensity distribution at the siuface of spherical gold nanoparticle with radius of 50 nm, calculated by FDTD technique. The incident field (1,0,0) was polarized along the y-axis the field monitor plane is perpendicular to the wave propagation direction (z-axis) and located at a distance of 70 nm from the center of the sphere...

Spherical gold nanoparticles coated with poly(N-isopropylacrylamide) (PNIPAM) grafts have been synthesized by controlled radical polymerization. The polymerization of N-isopropylacrylamide was initiated from the surface of the nanoparticles modified with 4-cyanopentanoic acid dithiobenzoate for reversible addition-fragmentation chain-transfer polymerization. The mean diameter of the Au core was 3.2 nm, as observed by means of high-resolution transmission electron microscopy [90]. 

Cseh and Mehl at last showed that quasi-spherical gold nanoparticles are capable of forming genuine liquid crystalline phases. The approach they used was to decorate gold nanoparticles (1.6-2 nm in diameter) with a mixed monolayer of... 

Delapierre, T.M., Majimel, J., Momet, S., Dngnet, E., and Ravaine, S. 2008. Synthesis of non-spherical gold nanoparticles. Gold Bulletin, 41 195-207. 

Hartling, T., Reichenbach, P. and Eng, L. M. (2007). Near-field coupling of a single fluorescent molecule and a spherical gold nanoparticle. Opt. Express 15 12806-12817. 

When cells are mixed with gold nanoparticle suspension, the nanoparticles are located in the vicinity of cells in the extracellular region. Figure 20.15 shows a comparison of the protein fluorescence spectra of whole cells with and without spherical gold nanoparticles. Obviously gold nanoparticles quench the fluorescence of cells at their protein bands when excited at protein absorption wavelength of 280 nm. There are no obvious differoices between normal cells and cancer cells. 

Number of gold atoms in a spherical gold nanoparticle... 

Figure 16.9 Transient absorption spectra of 15 nm spherical gold nanoparticles after excitation at 400 nm with 100 fs laser pulses, recorded as different delay times. Also shown is the steady-state UV/Vis-absorption spectrum of the colloidal gold solution. The inset shows the decay of the transient bleach when the particles are monitored at the hleach maximum at 520 nm. Fitting of the decay curve yields electron-phonon and phonon-phonon relaxation times of 3.1 and 90 ps, respectively. (Reproduced with permission from S. Link and M. El-Sayed, 1999. J. Phys. Chem. B 103 8410 8426. Copyright 1999 American Chemical Society.)...

Figure 16.10 Power dependence of the electron-phonon relaxation time. Part (a) shows the results for a 15 nm spherical gold nanoparticle after 400 nm excitation. The bleach recovery is monitored at the bleach maximum of 520 nm. The decay curves were fitted with lifetimes of 1.5, 2.0, 3.3, and 3.6 ps for excitation powers of 50, 80, 100, and 160nj, respectively. Part (b) shows a plot of the electron-phonon relaxation times against the relative pump power. Extrapolation to zero laser power yields a decay time of 690 + 100 fs for 400 nm excitation. The result for 630 nm excitation is included as well, which features a hmiting decay time of 830 + 100 fs. This result corresponds to an electron-phonon couphng constant of around 2.5 + 0.5 X 10 Wm At high laser powers the bleach also shows a long time component as seen by the offset of the decay curves in (a). This corresponds to the phonon-phonon relaxation, which occurs on a time scale of 100 ps. The amphtude ratio of the phonon-phonon to the electron-phonon relaxation time increases with increasing power, as shown in (c). (Reproduced with permission from S. Link and M. El-Sayed, 1999. J. Phys. Chem. B 103 8410-8426. Copyright 1999 American Chemical Society.)...

Figure 16.11 shows the simulated bleach of the plasmon absorption of spherical gold nanoparticles assuming a temperature change AT of either 10 K or 5000 K. It is apparent that the line width of the bleach is much broader for a larger change in the electron distribution. 

Figure 4.1 shows extinction spectra for spherical gold nanoparticles, with diameters of 20 and 100 nm, suspended in water. Gold nanoparticles with diameters of 20 and 100 nm exhibit broad extinction bands near 520 and 580 nm, respectively. Spectral features of the particles are well reproduced by Mie theory (Fig. 4.1b), and the bands are assigned to plasmon resonances. As mentioned, Mie theory gives rigorous solutions for spherical nanoparticles, and thus discrepancy between the observation and... 

Fig. 4.1 Far-field extinction spectra of spherical gold nanoparticles in water solution. Solid line-. 20 nm. Dotted line-. 100 nm. (a) Observation and (b) calculation by Mie theory...

Near-Field Transmission Measurement of Spherical Gold Nanoparticles [67]... 

Fig. 4.6 (a) Near-field transmission spectmm of a spherical gold nanoparticle (diameter 100 nm). (b,c) Near-field transmission images taken at 580 and 720 nm, respectively. Scale bar 100 nm... 

Fig. 4.17 (a,b) Calculated optical field distributions near a dimer of spherical gold nanoparticles (diameter 100 nm). Arrows indicate the incident polarization, (c) Topography of single and aggregated gold nanoparticles, (d) Two-photon excitation image of the sample (c) taken with incident polarization indicated by the arrow. Scale bars 1(X) nm... 

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