The Immersion Grating Infrared Spectrometer (IGRINS) is a compact high-resolution near-infrared cross-dispersed spectrograph whose primary disperser is a silicon immersion grating. IGRINS covers the entire portion of the wavelength range between 1.45 and 2.45μm that is accessible from the ground and does so in a single exposure with a resolving power of 40,000. Individual volume phase holographic (VPH) gratings serve as cross-dispersing elements for separate spectrograph arms covering the H and K bands. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is 1ʺ x 15ʺ and the plate scale is 0.27ʺ pixel -1 . The spectrograph employs two 2048 x 2048 pixel Teledyne Scientific & Imaging HAWAII-2RG detectors with SIDECAR ASIC cryogenic controllers. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be only 25mm, which permits a moderately sized (0.96m x 0.6m x 0.38m) rectangular cryostat to contain the entire spectrograph. The fabrication and assembly of the optical and mechanical components were completed in 2013. We describe the major design characteristics of the instrument including the system requirements and the technical strategy to meet them. We also present early performance test results obtained from the commissioning runs at the McDonald Observatory.
The ever-growing demand for hard drives with greater storage density has motivated a technology shift from continuous magnetic media to patterned media hard disks, which are expected to be implemented in future generations of hard disk drives to provide data storage at densities exceeding 1012 bits/in.2. Step and flash imprint lithography (S-FIL) technology has been employed to pattern the hard disk substrates. This article discusses the infrastructure required to enable S-FIL in high-volume manufacturing, namely, fabrication of master templates, template replication, high-volume imprinting with precisely controlled residual layers, and dual-sided imprinting. Imprinting of disks is demonstrated with substrate throughput currently as high as 180 disks/h (dual sided). These processes are applied to patterning hard disk substrates with both discrete tracks and bit-patterned designs.
Time-resolved FTIR has been used to study the photodissociation of NO2 at photolysis wavelengths of lambda = 266, 282, 295, 308, 320 and 327 nm. Nascent vibrational distributions of the NO(v) fragment have been determined at all wavelengths: 266 nm photolysis populates NO(v = 1-7) and shows a distribution that is inverted at v = 5, whereas 327 nm photolysis populates NO(v = 1-3) and is inverted at v = 2. Surprisal plots were performed on the nascent distributions presented in this work and on all data sets available in the literature in the range 266-370 nm in order to parameterise the wavelength dependence of the nascent distribution of NO(v) from NO2 photolysis. In general, the surprisal parameter was found to be a linear function of wavelength and was used to generate a simple model for the wavelength dependence of the nascent distribution of NO(v) in the region lambda = 265-372.5 nm. The results give a more accurate parameterisation of the formation of NO(v) of use in atmospheric modelling.
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