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Monitoring Chemical Reactions with Terahertz Rotational Spectroscopy

Swearer, Dayne F. and Gottheim, Samuel and Simmons, Jay G. and Phillips, Dane J. and Kale, Matthew J. and McClain, Michael J. and Christopher, Phillip and Halas, Naomi J. and Everitt, Henry O. (2018) Monitoring Chemical Reactions with Terahertz Rotational Spectroscopy. ACS Photonics, 5 (8). pp. 3097-3106. ISSN 2330-4022.

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Rotational spectroscopy is introduced as a new in situ method for monitoring gas-phase reactants and products during chemical reactions. Exploiting its unambiguous molecular recognition specificity and extraordinary detection sensitivity, rotational spectroscopy at terahertz frequencies was used to monitor the decomposition of carbonyl sulfide (OCS) over an aluminum nanocrystal (AlNC) plasmonic photocatalyst. The intrinsic surface oxide on AlNCs is discovered to have a large number of strongly basic sites that are effective for mediating OCS decomposition. Spectroscopic monitoring revealed two different photothermal decomposition pathways for OCS, depending on the absence or presence of H_2O. The strength of rotational spectroscopy is witnessed through its ability to detect and distinguish isotopologues of the same mass from an unlabeled OCS precursor at concentrations of <1 nanomolar or partial pressures of <10 μTorr. These attributes recommend rotational spectroscopy as a compelling alternative for monitoring gas-phase chemical reactants and products in real time.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Swearer, Dayne F.0000-0003-0274-4815
Kale, Matthew J.0000-0002-3039-3111
Christopher, Phillip0000-0002-4898-5510
Halas, Naomi J.0000-0002-8461-8494
Everitt, Henry O.0000-0002-8141-3768
Additional Information:© 2018 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: March 16, 2018; Published: May 18, 2018. The authors thank C. Neese and M. Reish for discussions regarding rotational spectroscopy, J. Yang, A. Alabastri, and P. Nordlander for discussions regarding photothermal heating of the Al NCs in vacuo, and Hossein Robatjazi for the instrument schematic in Figure 1a. This work was funded by the Air Force Office of Scientific Research Multidisciplinary Research Program of the University Research Initiative (AFOSR MURI FA9550-15-1-0022), the Army Research Office (MURI W911NF-12-1-0407), Defense Threat Reduction Agency (HDTRA 1-16-1-0042), the Army Aviation and Missile RD&E Center In-house Laboratory Innovative Research program, and the Welch Foundation under grant C-1220 (N.J.H.). D.F.S. acknowledges the National Science Foundation for a Graduate Research Fellowship under grant no. 1450681. Author Contributions: The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Author Contributions: D. F. Swearer and S. Gottheim contributed equally. The authors declare no competing financial interest.
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)FA9550-15-1-0022
Army Research Office (ARO)W911NF-12-1-0407
Defense Threat Reduction AgencyHDTRA 1-16-1-0042
Army Aviation and Missile RD&E CenterUNSPECIFIED
Robert A. Welch FoundationC-1220
NSF Graduate Research FellowshipDGE-1450681
Subject Keywords:plasmonics, photocatalysis, rotational spectroscopy, carbonyl sulfide, aluminum nanocrystals
Issue or Number:8
Record Number:CaltechAUTHORS:20180521-075659625
Persistent URL:
Official Citation:Monitoring Chemical Reactions with Terahertz Rotational Spectroscopy. Dayne F. Swearer, Samuel Gottheim, Jay G. Simmons, Dane J. Phillips, Matthew J. Kale, Michael J. McClain, Phillip Christopher, Naomi J. Halas, and Henry O. Everitt. ACS Photonics 2018 5 (8), 3097-3106. DOI: 10.1021/acsphotonics.8b00342
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86487
Deposited By: Tony Diaz
Deposited On:21 May 2018 16:03
Last Modified:03 Oct 2019 19:44

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