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  1. Article ; Online: Use of the complete basis set limit for computing highly accurate ab initio dipole moments.

    Conway, Eamon K / Gordon, Iouli E / Polyansky, Oleg L / Tennyson, Jonathan

    The Journal of chemical physics

    2020  Volume 152, Issue 2, Page(s) 24105

    Abstract: Calculating dipole moments with high-order basis sets is generally only possible for the light molecules, such as water. A simple, yet highly effective strategy of obtaining high-order dipoles with small, computationally less expensive basis sets is ... ...

    Abstract Calculating dipole moments with high-order basis sets is generally only possible for the light molecules, such as water. A simple, yet highly effective strategy of obtaining high-order dipoles with small, computationally less expensive basis sets is described. Using the finite field method for computing dipoles, energies calculated with small basis sets can be extrapolated to produce dipoles that are comparable to those obtained in high order calculations. The method reduces computational resources by approximately 50% (allowing the calculation of reliable dipole moments for larger molecules) and simultaneously improves the agreement with experimentally measured infrared transition intensities. For atmospherically important molecules, which are typically too large to consider the use of large basis sets, this procedure will provide the necessary means of improving calculated spectral intensities by several percent.
    Language English
    Publishing date 2020-01-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/1.5135931
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Fitting potential energy and induced dipole surfaces of the van der Waals complex CH

    Finenko, Artem A / Chistikov, Daniil N / Kalugina, Yulia N / Conway, Eamon K / Gordon, Iouli E

    Physical chemistry chemical physics : PCCP

    2021  Volume 23, Issue 34, Page(s) 18475–18494

    Abstract: We present an extensive study of the five-dimensional potential energy and induced dipole surfaces of the ... ...

    Abstract We present an extensive study of the five-dimensional potential energy and induced dipole surfaces of the CH
    Language English
    Publishing date 2021-08-18
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d1cp02161c
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Book ; Online: Cavity ring-down spectroscopy of water vapor in the near-UV region

    Yang, Qing-Ying / Conway, Eamon K. / Liang, Hui / Gordon, Iouli E. / Tan, Yan / Hu, Shui-Ming

    eISSN: 1867-8548

    2022  

    Abstract: Water vapor absorption in the near-ultraviolet region is essential to describe the energy budget of Earth, but little spectroscopic information is available since it is a challenging spectral region for both experimental and theoretical studies. A ... ...

    Abstract Water vapor absorption in the near-ultraviolet region is essential to describe the energy budget of Earth, but little spectroscopic information is available since it is a challenging spectral region for both experimental and theoretical studies. A continuous-wave cavity ring-down spectroscopic experiment was built to record absorption lines of water vapor around 415 nm. With a minimum detectable absorption coefficient of 4 × 10 −10 cm −1 , 40 rovibrational transitions of H 16 2 O were observed in this work, and 27 of them were assigned to the (224), (205), (710), (304), (093), (125), and (531) vibrational bands. A comparison of line positions and intensities determined in this work to the most recent HITRAN database is presented. Water vapor absorption cross-sections near 415 nm were calculated based on our measurements, which vary between 1 × 10 −26 and 5 × 10 −26 cm 2 /molecule. These data will also significantly impact the spectroscopy detection of trace gas species in the near -UV region.
    Subject code 333
    Language English
    Publishing date 2022-05-31
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Book ; Online: Level0 to Level1B processor for MethaneAIR

    Conway, Eamon K. / Souri, Amir H. / Benmergui, Joshua / Sun, Kang / Liu, Xiong / Staebell, Carly / Chan Miller, Christopher / Franklin, Jonathan / Samra, Jenna / Wilzewski, Jonas / Roche, Sebastien / Luo, Bingkun / Chulakadabba, Apisada / Sargent, Maryann / Hohl, Jacob / Daube, Bruce / Gordon, Iouli / Chance, Kelly / Wofsy, Steven

    eISSN: 1867-8548

    2024  

    Abstract: This work presents the development of the MethaneAIR Level0–Level1B processor, which converts raw L0 data to calibrated and georeferenced L1B data. MethaneAIR is the airborne simulator for MethaneSAT, a new satellite under development by MethaneSAT LLC, ... ...

    Abstract This work presents the development of the MethaneAIR Level0–Level1B processor, which converts raw L0 data to calibrated and georeferenced L1B data. MethaneAIR is the airborne simulator for MethaneSAT, a new satellite under development by MethaneSAT LLC, a subsidiary of the Environmental Defense Fund (EDF). MethaneSAT's goals are to precisely map over 80 % of the production sources of methane from oil and gas fields across the globe to an accuracy of 2–4 ppb on a 2 km 2 scale. Efficient algorithms have been developed to perform dark corrections, estimate the noise, radiometrically calibrate data, and correct stray light. A forward model integrated into the L0–L1B processor is demonstrated to retrieve wavelength shifts during flight accurately. It is also shown to characterize the instrument spectral response function (ISRF) changes occurring at each sampled spatial footprint. We demonstrate fast and accurate orthorectification of MethaneAIR data in a three-step process: (i) initial orthorectification of all observations using aircraft avionics, a simple camera model, and a medium-resolution digital elevation map; (ii) registration of oxygen (O 2 ) channel grayscale images to reference Multispectral Instrument (MSI) band 11 imagery via Accelerated-KAZE (A-KAZE) feature extraction and linear transformation, with similar co-registration of methane (CH 4 ) channel grayscale images to the registered O 2 channel images; and finally (iii) optimization of the aircraft position and attitude to the registered imagery and calculation of viewing geometry. This co-registration technique accurately orthorectifies each channel to the referenced MSI imagery. However, in the pixel domain, radiance data for each channel are offset by almost 150–200 across-track pixels (rows) and need to be aligned for the full-physics or proxy retrievals where both channels are simultaneously used. We leveraged our orthorectification tool to identify tie points with similar geographic locations in both CH 4 and O 2 images in order to produce shift ...
    Subject code 333
    Language English
    Publishing date 2024-02-29
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: A highly accurate

    Conway, Eamon K / Kyuberis, Aleksandra A / Polyansky, Oleg L / Tennyson, Jonathan / Zobov, Nikolai F

    The Journal of chemical physics

    2018  Volume 149, Issue 8, Page(s) 84307

    Abstract: A new global and highly ... ...

    Abstract A new global and highly accurate
    Language English
    Publishing date 2018-09-11
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/1.5043545
    Database MEDical Literature Analysis and Retrieval System OnLINE

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