Universität zu Köln

Lee, Kin Long Kelvin, Thorwirth, Sven, Martin-Drumel, Marie-Aline ORCID: 0000-0002-5460-4294 and McCarthy, Michael C. (2019). Generation and structural characterization of Ge carbides GeCn (n=4, 5, 6) by laser ablation, broadband rotational spectroscopy, and quantum chemistry. Phys. Chem. Chem. Phys., 21 (35). S. 18911 - 18920. CAMBRIDGE: ROYAL SOC CHEMISTRY. ISSN 1463-9084

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Abstract

Following the recent discovery of T-shaped GeC2, rotational spectra of three larger Ge carbides, linear GeC4, GeC5, and GeC6 have been observed using chirped pulse and cavity Fourier transform microwave spectroscopy and a laser ablation molecule source, guided by new high-level quantum chemical calculations of their molecular structure. Like their isovalent Si-bearing counterparts, Ge carbides with an even number of carbon atoms beyond GeC2 are predicted to possess (1)sigma ground electronic states, while odd-numbered carbon chains are generally (3)sigma; all are predicted to be highly polar. For the three new molecules detected in this work, rotational lines of four of the five naturally occurring Ge isotopic variants have been observed between 6 and 22 GHz. Combining these measurements with ab initio force fields, the Ge-C bond lengths have been determined to high precision: the derived values of 1.776 angstrom for GeC4, 1.818 angstrom for GeC5, and 1.782 angstrom for GeC6 indicate a double bond between these two atoms. Somewhat surprisingly, the spectrum of GeC5 very closely resembles that of a (1)sigma molecule, implying a spin-spin coupling constant lambda in excess of 770 GHz for this radical, a likely consequence of the large spin-orbit constant of atomic Ge (similar to 1000 cm(-1)). A systematic comparison between the production of SiCn and GeCn chains by laser ablation has also been undertaken. The present work suggests that other large metal-bearing molecules may be amenable to detection by similar means.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Lee, Kin Long Kelvin UNSPECIFIED UNSPECIFIED UNSPECIFIED Thorwirth, Sven UNSPECIFIED UNSPECIFIED UNSPECIFIED Martin-Drumel, Marie-Aline UNSPECIFIED orcid.org/0000-0002-5460-4294 UNSPECIFIED McCarthy, Michael C. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-141108
DOI:	10.1039/c9cp03607e
Journal or Publication Title:	Phys. Chem. Chem. Phys.
Volume:	21
Number:	35
Page Range:	S. 18911 - 18920
Date:	2019
Publisher:	ROYAL SOC CHEMISTRY
Place of Publication:	CAMBRIDGE
ISSN:	1463-9084
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CONSISTENT BASIS-SETS; CORRELATED MOLECULAR CALCULATIONS; GERMANIUM-CARBON CLUSTERS; GAUSSIAN-BASIS SETS; LINEAR SILICON CARBIDES; VIBRATIONAL-SPECTRA; DIPOLE-MOMENT; MODE; TRANSITION; IDENTIFICATION Multiple languages Chemistry, Physical; Physics, Atomic, Molecular & Chemical Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14110