Davydov split PL emission and EPR correlation in β-MnS layered CdS nanorods

Sambandam, Balaji ; Manoharan, Periakaruppan T. (2009) Davydov split PL emission and EPR correlation in β-MnS layered CdS nanorods Journal of Physical Chemistry C, 113 (22). pp. 9486-9496. ISSN 1932-7447

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp9013042

Related URL: http://dx.doi.org/10.1021/jp9013042

Abstract

A comparison of manganese activated CdS nanorods with the nonactivated ones prepared by simple chemical methods in micellar medium reveals quantum confinement and blue shift in optical spectroscopy as a function of Mn2+. Powder XRD of all samples reveals orientation along the 002 plane, confirmed by HRTEM. Nonactivated CdS gives a blue band edge emission at 455 nm in the PL spectrum getting quenched on Mn2+ addition. The PL spectra of Mn2+ added CdS exhibit first an emission at 367.7 nm, which later gets subjected to Davydov splitting with a separation of ∼ 0.045 eV, the singlet intensity decreasing and the doublet intensity increasing with Mn2+ input. This PL property is manifested in EPR as due to two different Mn2+ environments: (i) individual tetrahedrally coordinated uncoupled Mn2+ ions; (ii) Mn2+−Mn2+ physical dimer moieties. These are interpreted to arise from (i) the formation of a first layer of MnS on a CdS surface and (ii) the latter due to a second layer of MnS on top of the first to form MnS−MnS dimers. Mn2+ is present as metastable β-MnS. The Davydov splitting is accompanied by a small energy shift. The double layer formation is confirmed by a bleaching experiment. Also noted is a low intensity band edge emission of CdS perturbed by Mn2+ blue-shifted from the quenched 455 nm emission. ICP and EDS confirm the purity of samples.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:95775
Deposited On:26 Dec 2012 05:42
Last Modified:26 Dec 2012 05:43

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