8 research outputs found
Ab Initio Spatial Phase Retrieval via Fluorescence Intensity Triple Correlations
A complete method for ab initio phase retrieval via spatial intensity triple
correlations is described. Simulations demonstrate accurate phase retrieval for
clusters of classical incoherent emitters
C-phycocyanin as a highly attractive model system in protein crystallography: unique crystallization properties and packing-diversity screening
The unique crystallization properties of the antenna protein C-phycocyanin (C-PC) from the thermophilic cyanobacterium Thermosynechococcus elongatus are reported and discussed. C-PC crystallizes in hundreds of significantly different conditions within a broad pH range and in the presence of a wide variety of precipitants and additives. Remarkably, the crystal dimensions vary from a few micrometres, as used in serial crystallography, to several hundred micrometres, with a very diverse crystal morphology. More than 100 unique single-crystal X-ray diffraction data sets were collected from randomly selected crystals and analysed. The addition of small-molecule additives revealed three new crystal packings of C-PC, which are discussed in detail. The high propensity of this protein to crystallize, combined with its natural blue colour and its fluorescence characteristics, make it an excellent candidate as a superior and highly adaptable model system in crystallography. C-PC can be used in technical and methods development approaches for X-ray and neutron diffraction techniques, and as a system for comprehending the fundamental principles of protein crystallography
Magneto-optical properties of InSb for infrared spectral filtering
We present measurements of the Faraday effect in n-type InSb. The Verdet
coefficient was determined for a range of carrier concentrations near
in the = 8 m - 12 m long-wave infrared
regime. The absorption coefficient was measured and a figure of merit
calculated for each sample. From these measurements, we calculated the carrier
effective mass and illustrate the variation of the figure of merit with
wavelength. A method for creating a tunable bandpass filter via the Faraday
rotation is discussed along with preliminary results from a prototype device
Transient vibration and product formation of photoexcited CS<sub>2</sub> measured by time-resolved X-ray scattering
We have observed details of the internal motion and dissociation channels in photoexcited carbon disulfide (CS2) using time-resolved x-ray scattering (TRXS). Photoexcitation of gas-phase CS2 with a 200 nm laser pulse launches oscillatory bending and stretching motion, leading to dissociation of atomic sulfur in under a picosecond. During the first 300 fs following excitation, we observe significant changes in the vibrational frequency as well as some dissociation of the C–S bond, leading to atomic sulfur in the both 1D and 3P states. Beyond 1400 fs, the dissociation is consistent with primarily 3P atomic sulfur dissociation. This channel-resolved measurement of the dissociation time is based on our analysis of the time-windowed dissociation radial velocity distribution, which is measured using the temporal Fourier transform of the TRXS data aided by a Hough transform that extracts the slopes of linear features in an image. The relative strength of the two dissociation channels reflects both their branching ratio and differences in the spread of their dissociation times. Measuring the time-resolved dissociation radial velocity distribution aids the resolution of discrepancies between models for dissociation proposed by prior photoelectron spectroscopy work