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Title: Cooperative enhancement of the nonlinear optical response in conjugated energetic materials: A TD-DFT study

Conjugated energetic molecules (CEMs) are a class of explosives with high nitrogen content that posses both enhanced safety and energetic performance properties and are ideal for direct optical initiation. As isolated molecules, they absorb within the range of conventional lasers. Crystalline CEMs are used in practice, however, and their properties can differ due to intermolecular interaction. Herein, time-dependent density functional theory was used to investigate one-photon absorption (OPA) and two-photon absorption (TPA) of monomers and dimers obtained from experimentally determined crystal structures of CEMs. OPA scales linearly with the number of chromophore units, while TPA scales nonlinearly, where a more than 3-fold enhancement in peak intensity, per chromophore unit, is calculated. Cooperative enhancement depends on electronic delocalization spanning both chromophore units. An increase in sensitivity to nonlinear laser initiation makes these materials suitable for practical use. This is the first study predicting a cooperative enhancement of the nonlinear optical response in energetic materials composed of relatively small molecules. Finally, the proposed model quantum chemistry is validated by comparison to crystal structure geometries and the optical absorption of these materials dissolved in solution.
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [3] ;  [4] ;  [3] ;  [3]
  1. Univ. of Southern California, Los Angeles, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Stanford Univ., Stanford, CA (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Univ. of Southern California, Los Angeles, CA (United States)
Publication Date:
Report Number(s):
LA-UR-17-21526
Journal ID: ISSN 0021-9606; JCPSA6; TRN: US1700591
Grant/Contract Number:
AC52-06NA25396; SC0014429
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 11; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1351991
Alternate Identifier(s):
OSTI ID: 1348038