scholarly journals Mid-infrared interferometry with high spectral resolution

Author(s):  
Edward H. Wishnow ◽  
William Mallard ◽  
Vikram Ravi ◽  
Sean Lockwood ◽  
Walt Fitelson ◽  
...  
2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Muhammad A. Abbas ◽  
Qing Pan ◽  
Julien Mandon ◽  
Simona M. Cristescu ◽  
Frans J. M. Harren ◽  
...  

AbstractDual-comb spectroscopy can provide broad spectral bandwidth and high spectral resolution in a short acquisition time, enabling time-resolved measurements. Specifically, spectroscopy in the mid-infrared wavelength range is of particular interest, since most of the molecules have their strongest rotational-vibrational transitions in this “fingerprint” region. Here we report time-resolved mid-infrared dual-comb spectroscopy, covering ~300 nm bandwidth around 3.3 μm with 6 GHz spectral resolution and 20 μs temporal resolution. As a demonstration, we study a CH4/He gas mixture in an electric discharge, while the discharge is modulated between dark and glow regimes. We simultaneously monitor the production of C2H6 and the vibrational excitation of CH4 molecules, observing the dynamics of both processes. This approach to broadband, high-resolution, and time-resolved mid-infrared spectroscopy provides a new tool for monitoring the kinetics of fast chemical reactions, with potential applications in various fields such as physical chemistry and plasma/combustion analysis.


2021 ◽  
Author(s):  
Karolis Madeikis ◽  
Robertas Kananavicius ◽  
Rokas Danilevicius ◽  
Audrius Zaukevicius ◽  
Januskevicius Regimantas ◽  
...  

2018 ◽  
Vol 07 (04) ◽  
pp. 1840013 ◽  
Author(s):  
M. J. Richter ◽  
C. N. DeWitt ◽  
M. McKelvey ◽  
E. Montiel ◽  
R. McMurray ◽  
...  

The Echelon-cross-echelle spectrograph (EXES) is a high spectral resolution, mid-infrared spectrograph designed for and operated on the Stratospheric Observatory for Infrared Astronomy (SOFIA). EXES has multiple operational modes, but is optimized for high spectral resolution. The heart of the instrument is a one meter long, diamond-machined echelon grating. EXES also uses a 10242 Si:As detector optimized for low-background flux. We will discuss the design, operation and performance of EXES.


2019 ◽  
Author(s):  
Tiziano Maestri ◽  
William Cossich ◽  
Iacopo Sbrolli

Abstract. A new Cloud Identification and Classification algorithm, named CIC, is presented. CIC is a machine-learning algorithm, based on Principal Component Analysis, able to perform a cloud detection and scene classification using a univariate distribution and a threshold, which serves as a binary classifier. CIC is tested on a widespread synthetic dataset of high spectral resolution radiances in the far and mid infrared part of the spectrum simulating measures from the ESA Earth Explorer Fast Track 9 competing mission FORUM (Far Infrared Outgoing Radiation Understanding and Monitoring) that is currently (2018/19) undergoing the industrial and scientific Phase-A studies. Simulated spectra are representatives of many diverse climatic areas, ranging from the tropical to polar regions. Application of the algorithm to the synthetic dataset provides high scores for clear/cloud identification, especially when optimisation processes are performed. One of the main results consists in pointing out the high information content of spectral radiance in the far-infrared region of the electromagnetic spectrum to identify cloudy scenes specifically thin cirrus clouds.


1987 ◽  
Vol 122 ◽  
pp. 553-554
Author(s):  
U. Schrey ◽  
S. Drapatz ◽  
H.U. Käufl ◽  
H. Rothermel ◽  
S. K. Ghosh

Heterodyne spectroscopy at 11 μm combines high spectral resolution (λ/Δ λ ~106), high spatial resolution (< 1 arcsec at 3 m telescopes) and high penetration depth. Therefore, it seems promising to use it also for the investigation of bright circumstellar atmospheres.


2019 ◽  
Vol 12 (7) ◽  
pp. 3521-3540 ◽  
Author(s):  
Tiziano Maestri ◽  
William Cossich ◽  
Iacopo Sbrolli

Abstract. A new cloud identification and classification algorithm named CIC is presented. CIC is a machine learning algorithm, based on principal component analysis, able to perform a cloud detection and scene classification using a univariate distribution of a similarity index that defines the level of closeness between the analysed spectra and the elements of each training dataset. CIC is tested on a widespread synthetic dataset of high spectral resolution radiances in the far- and mid-infrared part of the spectrum, simulating measurements from the Fast Track 9 mission FORUM (Far-Infrared Outgoing Radiation Understanding and Monitoring), competing for the ESA Earth Explorer programme, which is currently (2018 and 2019) undergoing industrial and scientific Phase A studies. Simulated spectra are representatives of many diverse climatic areas, ranging from the tropical to polar regions. Application of the algorithm to the synthetic dataset provides high scores for clear or cloud identification, especially when optimisation processes are performed. One of the main results consists of pointing out the high information content of spectral radiance in the far-infrared region of the electromagnetic spectrum to identify cloudy scenes, specifically thin cirrus clouds. In particular, it is shown that hit scores for clear and cloudy spectra increase from about 70 % to 90 % when far-infrared channels are accounted for in the classification of the synthetic dataset for tropical regions.


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