Donor identification in bulk GaAs by Fourier transform photoluminescence

1991 ◽  
Vol 69 (3-4) ◽  
pp. 427-431 ◽  
Author(s):  
D. J. S. Beckett ◽  
M. K. Nissen ◽  
M. L. W. Thewalt
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
High Purity ◽  
Chemical Shifts ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
High Magnetic Fields ◽  
Bulk Gaas ◽  
Donor Identification ◽  
Small Chemical

The identification of substitutional shallow donors in GaAs by optical techniques has been problematic because of the extremely small chemical shifts of these effective-masslike impurities. Photoluminescence has been successfully applied in identifying donors in high-purity epitaxial material through the painstaking use of high-resolution spectroscopy, high-magnetic fields, and resonant excitation. Relatively little work has been done in bulk GaAs, where the broadened transitions hinder the resolution of different species. Recently we demonstrated that the high resolution and high-signal throughput obtained with Fourier transform photoluminescence (FTPL) gives superior results for epitaxial material. In this report we show that the advantages of FTPL can also be applied to reliable donor identification in bulk GaAs.

scholarly journals Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

2020 ◽  
Vol 495 (1) ◽  
pp. 224-237 ◽  
Author(s):  
Siddharth Gandhi ◽  
Matteo Brogi ◽  
Sergei N Yurchenko ◽  
Jonathan Tennyson ◽  
Phillip A Coles ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Sections ◽  
Cross Correlation ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Pressure Broadening ◽  
Spectral Signatures ◽  
Hot Jupiters ◽  
Wide Range ◽  
Infrared Spectral

ABSTRACT High-resolution spectroscopy (HRS) has been used to detect a number of species in the atmospheres of hot Jupiters. Key to such detections is accurately and precisely modelled spectra for cross-correlation against the R ≳ 20 000 observations. There is a need for the latest generation of opacities which form the basis for high signal-to-noise detections using such spectra. In this study we present and make publicly available cross-sections for six molecular species, H2O, CO, HCN, CH4, NH3, and CO2 using the latest line lists most suitable for low- and high-resolution spectroscopy. We focus on the infrared (0.95–5 μm) and between 500 and 1500 K where these species have strong spectral signatures. We generate these cross-sections on a grid of pressures and temperatures typical for the photospheres of super-Earth, warm Neptunes, and hot Jupiters using the latest H2 and He pressure broadening. We highlight the most prominent infrared spectral features by modelling three representative exoplanets, GJ 1214 b, GJ 3470 b, and HD 189733 b, which encompass a wide range in temperature, mass, and radii. In addition, we verify the line lists for H2O, CO, and HCN with previous high-resolution observations of hot Jupiters. However, we are unable to detect CH4 with our new cross-sections from HRS observations of HD 102195 b. These high-accuracy opacities are critical for atmospheric detections with HRS and will be continually updated as new data become available.

scholarly journals Design and laboratory performance of a fiber-fed Fourier transform spectrograph based on off-the-shelf components for astronomical medium and high-resolution spectroscopy

2022 ◽  
Vol 61 (01) ◽  
Author(s):  
Pornapa Artsang ◽  
Christophe Buisset ◽  
Panomsak Meemon ◽  
Pakakaew Rittipruk ◽  
Sirinrat Sithajan ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
High Resolution Spectroscopy ◽  
Laboratory Performance

Instrumental Resolution Considerations for Fourier Transform Infrared Gas-Phase Spectroscopy

1997 ◽  
Vol 51 (8) ◽  
pp. 1159-1169 ◽  
Author(s):  
P. Jaakkola ◽  
J. D. Tate ◽  
M. Paakkunainen ◽  
J. Kauppinen ◽  
P. Saarinen
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Gas Phase ◽  
Dynamic Range ◽  
Fourier Transform Infrared ◽  
High Signal ◽  
Low Resolution ◽  
Instrumental Resolution ◽  
Ft Ir ◽  
Gas Phase Spectroscopy

Instrumental resolution has a significant effect on the performance of Fourier transform infrared (FT-IR) spectrometers used for gasphase analysis. Low-resolution FT-IR spectroscopy offers some valuable advantages compared with the traditional high-resolution FT-IR gas-phase spectroscopy, especially in nonlaboratory environments. First, high signal-to-noise ratio (SNR) spectra can be acquired in field conditions without the use of traditional liquid nitrogen-cooled detectors. Second, the dynamic range for quantitative analysis is larger for low-resolution spectroscopy than for high-resolution due to the lower absorbance values and lower noise levels. Third, spectral analysis speed is increased and data storage requirements are substantially reduced. The purpose of this study was to investigate the effect of instrumental resolution on FT-IR gas-phase analysis. The effects of spectral resolution on sensitivity, selectivity, accuracy, precision, spectral overlap, dynamic range, and nonlinearity are separately discussed.

scholarly journals High-Resolution 3 μm Spectroscopy of Extreme Carbon Stars

1987 ◽  
Vol 120 ◽  
pp. 387-390
Author(s):  
J.-P. Maillard ◽  
S.C. Foster ◽  
T. Amano ◽  
P.A. Feldman
Keyword(s):  
Fourier Transform ◽  
Silicon Nitride ◽  
High Resolution ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Fourier Transform Spectrometer ◽  
Carbon Stars ◽  
Signal To Noise ◽  
Fundamental Band ◽  
Upper Limits

We have used the Cassegrain-focus Fourier Transform Spectrometer of the Canada-France-Hawaii Telescope to record high-resolution (0.03 cm−1), high signal-to-noise ratio spectra of the extreme carbon stars IRC+10°216 and CIT6 in the 2850–3100 cm−1 region. Upper limits were obtained for the column densities of silicon nitride (2-0 band of the A-X system), ethylene (ν11 fundamental band at ν0 = 2988.7 cm−1), and ethane (ν7 fundamental band at ν0 = 2985.4 cm−1).

scholarly journals Lithium Abundances of Solar-Type Stars: A Critical Application of High Signal-to-Noise, High Resolution Spectroscopy

1988 ◽  
Vol 132 ◽  
pp. 381-386
Author(s):  
David R. Soderblom
Keyword(s):  
High Resolution ◽  
The State ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Signal To Noise ◽  
High Quality ◽  
Essential Properties ◽  
Solar Type ◽  
Lithium Depletion

The study of lithium depletion in solar-type stars should help elucidate essential properties of convection in those objects. Recent high-quality observations have revealed extensive flaws in our understanding of this phenomenon. The state of our knowledge of Li depletion is reviewed, with a brief possible explanation of it all.

scholarly journals Remote sensing of exoplanetary atmospheres with ground-based high-resolution near-infrared spectroscopy

2019 ◽  
Vol 629 ◽  
pp. A109 ◽  
Author(s):  
D. Shulyak ◽  
M. Rengel ◽  
A. Reiners ◽  
U. Seemann ◽  
F. Yan
Keyword(s):  
Infrared Spectroscopy ◽  
Temperature Distribution ◽  
High Resolution ◽  
Near Infrared Spectroscopy ◽  
Atmospheric Chemistry ◽  
Near Infrared ◽  
Optimal Estimation ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Wide Range

Context. Thanks to the advances in modern instrumentation we have learned about many exoplanets that span a wide range of masses and composition. Studying their atmospheres provides insight into planetary origin, evolution, dynamics, and habitability. Present and future observing facilities will address these important topics in great detail by using more precise observations, high-resolution spectroscopy, and improved analysis methods. Aims. We investigate the feasibility of retrieving the vertical temperature distribution and molecular number densities from expected exoplanet spectra in the near-infrared. We use the test case of the CRIRES+ instrument at the Very Large Telescope which will operate in the near-infrared between 1 and 5 μm and resolving powers of R = 100 000 and R = 50 000. We also determine the optimal wavelength coverage and observational strategies for increasing accuracy in the retrievals. Methods. We used the optimal estimation approach to retrieve the atmospheric parameters from the simulated emission observations of the hot Jupiter HD 189733b. The radiative transfer forward model is calculated using a public version of the τ-REx software package. Results. Our simulations show that we can retrieve accurate temperature distribution in a very wide range of atmospheric pressures between 1 bar and 10−6 bar depending on the chosen spectral region. Retrieving molecular mixing ratios is very challenging, but a simultaneous observations in two separate infrared regions around 1.6 and 2.3 μm helps to obtain accurate estimates; the exoplanetary spectra must be of relatively high signal-to-noise ratio S∕N ≥ 10, while the temperature can already be derived accurately with the lowest value that we considered in this study (S∕N = 5). Conclusions. The results of our study suggest that high-resolution near-infrared spectroscopy is a powerful tool for studying exoplanet atmospheres because numerous lines of different molecules can be analyzed simultaneously. Instruments similar to CRIRES+ will provide data for detailed retrieval and will provide new important constraints on the atmospheric chemistry and physics.

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