View
Publication Type
Journal Article
UWI Author(s)
Author, Analytic
Fender, Nicolette S.; Kahwa, Ishenkumba A.
Author Affiliation, Ana.
Department of Chemistry
Article Title
Defects and luminescence behaviour of cubic F23 [NH4(18-Crown-6))4MnX4] [TlX4]2 (X = Cl, Br) crystals
Medium Designator
n/a
Connective Phrase
n/a
Journal Title
Journal of Solid State Chemistry
Translated Title
n/a
Reprint Status
Refereed
Date of Publication
2002
Volume ID
163
Issue ID
n/a
Page(s)
286-93
Language
n/a
Connective Phrase
n/a
Location/URL
n/a
ISSN
n/a
Notes
n/a
Abstract
Luminescence form [NH4(18-Crown-6))4MnBr4][TlBr4]2 (1), [NH4(18-Crown-6))4MnCl4][TlCl4]2 (2), [(NH4(18-Crown-6))2MnBr4] (3), and [(NH4(18-Crown-6))2MnCl4] (4) was studied in search of new insights regarding crystal defects in 2. Emission from 3 and 4 is normal Mn2+ (4T1(4G) 6A1); that of 2 (lmax 520 nm at ca. 300 K and 560 nm at 77 K) is unsual and temperature dependent. Thermal barriers (kJ/mol, assignment): green emission of 1 and 2, T < 150 K (12, NH4+ rotations), 150< T < 250 K (714, energy migration among [MnX4]2-), 250 < T < 300 K (2635, rotations of 18-Crown-6)); yellow emission of 2: T < 250 K (78, energy migration among [MnX4]2-), T < 250 K (29 kJ/mol, defect-to-Mn2+ (4T1(4G)) back energy transfer). Crystal data for 4: Space group P21/c; Z = 4; a = 20.173(1) ; c = 20.821(1) ; b = 98.782(5); V = 3741.9(8) 3; Rw = 0.059; R = 0.054.....
read more