Alexei Tcherniak
Rice University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Alexei Tcherniak.
Nano Letters | 2010
Alexei Tcherniak; J. W. Ha; Sergio Dominguez-Medina; Liane Siu Slaughter
In 1908, Gustav Mie solved Maxwells equations to account for the absorption and scattering of spherical plasmonic particles. Since then much attention has been devoted to the size dependent optical properties of metallic nanoparticles. However, ensemble measurements of colloidal solutions generally only yield the total extinction cross sections of the nanoparticles. Here, we show how Mies prediction on the size dependence of the surface absorption and scattering can be probed separately for the same gold nanoparticle by using two single particle spectroscopy techniques, (1) dark-field scattering and (2) photothermal imaging, which selectively only measure scattering and absorption, respectively. Combining the optical measurements with correlated scanning electron microscopy furthermore allowed us to measure the size of the spherical gold nanoparticles, which ranged from 43 to 274 nm in diameter. We found that even though the trend predicted by Mie theory is followed well by the experimental data over a large range of nanoparticle diameters, for small size variations changes in scattering and absorption intensities are dominated by factors other than those considered by Mie theory. In particular, spectral shifts of the plasmon resonance due to deviations from a spherical particle shape alone cannot explain the observed variation in absorption and scattering intensities.
Analytical Chemistry | 2009
Alexei Tcherniak; Carmen Reznik; Stephan Link; Christy F. Landes
We have evaluated the effect of varying three key parameters for Fluorescence Correlation Spectroscopy analysis, first in the context of a one species/one environment system, and then in a complex system composed of two species, or conversely, two environments. We establish experimentally appropriate settings for the (1) minimum lag time, (2) maximum lag time, and (3) averaging times over which an autocorrelation is carried out, as a function of expected diffusion decay time for a particular solute, and show that use of appropriate settings plays a critical role in recovering accurate and reliable decay times and resulting diffusion constants. Both experimental and simulated data were used to show that for a complex binary system, to extract accurate diffusion constants for both species, decay times must be bounded by adequate minimum and maximum lag times as dictated by the fast and slow diffusing species, respectively. We also demonstrate that even when constraints on experimental conditions do not permit achieving the necessary lag time limits for both of the species in a binary system, the accuracy of the recovered diffusion constant for the one species whose autocorrelation function is fully time-resolved is unaffected by uncertainty in fitting introduced by the presence of the second species.
Journal of Chemical Physics | 2009
Kevin Claytor; Saumyakanti Khatua; Jason M. Guerrero; Alexei Tcherniak; James M. Tour; Stephan Link
This paper presents a method for simultaneously determining multiple trajectories of single molecules from sequential fluorescence images in the presence of photoblinking. The tracking algorithm is computationally nondemanding and does not assume a model for molecular motion, which allows one to determine correct trajectories even when a distribution of movement speeds is present. We applied the developed procedure to the important problem of monitoring surface motion of single molecules under ambient conditions. By limiting the laser exposure using sample scanning confocal microscopy, long-time trajectories have been extracted without the use of oxygen scavengers for single fluorescent molecules. Comparison of the experimental results to simulations showed that the smallest diffusion constants extracted from the trajectories are limited by detector shot noise giving error in locating the positions of the individual molecules. The simulations together with the single molecule trajectories and distributions of diffusion constants allowed us therefore to distinguish between mobile and immobile molecules. Because the analysis algorithm only requires a time series of images, the procedure presented here can be used in conjunction with various imaging methodologies to study a wide range of diffusion processes.
Journal of Physical Chemistry C | 2011
Alexei Tcherniak; Sergio Dominguez-Medina; Wei-Shun Chang; Pattanawit Swanglap; Liane Siu Slaughter; Christy F. Landes; Stephan Link
Journal of Physical Chemistry C | 2010
Saumyakanti Khatua; Pramit Manna; Wei-Shun Chang; Alexei Tcherniak; Eric Friedlander; Eugene R. Zubarev; Stephan Link
Journal of Physical Chemistry C | 2010
Liane Siu Slaughter; Wei-Shun Chang; Pattanawit Swanglap; Alexei Tcherniak; Bishnu P. Khanal; Eugene R. Zubarev; Stephan Link
Journal of the American Chemical Society | 2008
Alexei Tcherniak; David Solis; Saumyakanti Khatua; Andrew Tangonan; T. Randall Lee; Stephan Link
The Journal of Physical Chemistry | 2012
Alexei Tcherniak; Sergio Dominguez-Medina; Wei-Shun Chang; Pattanawit Swanglap; Liane Siu Slaughter; Christy F. Landes; Stephan Link
Abstracts of Papersss of The American Chemical Society | 2011
Sergio Dominguez-Medina; Alexei Tcherniak; Wei-Shun Chang; Pattanawit Swanglap; Liane Siu Slaughter; Stephan Link
Abstracts of Papers of the American Chemical Society | 2010
Liane Siu Slaughter; Pattanawit Swanglap; Alexei Tcherniak; Wei-Shun Chang; Bishnu P. Khanal; Eugene R. Zubarev; Stephan Link