High field {sup 31}P ENDOR of MnAlPO{sub 4}-20: Direct evidence for framework substitution
The incorporation of Mn(II) into framework sites in the aluminophosphate zeotype AlPO{sub 4}-20, an analog of sodalite, has been investigated using pulsed electron nuclear double resonance (ENDOR) spectroscopy at 95 GHz. The field sweep echo-detected EPR spectrum showed the presence of a single Mn(II) site with a {sup 55}Mn hyperfine coupling of 8.7 mT. ENDOR spectra, recorded using the Mims and Davies sequences, consist of an {sup 27}Al signal at the Larmor frequency and a {sup 31}P Larmor frequency indicates that it originates from the M{sub s} = {+-}1/2 manifolds and that the interaction is primarily isotropic. The relatively large {sup 31}P hyperfine interaction and the weak interaction with {sup 27}Al provide unique and direct evidence for Mn(II) substitution of framework Al. X-band electron spin echo envelope modulation (ESEEM) measurements showed only signals at the {sup 1}H, {sup 14}N, {sup 27}Al, and {sup 31}P Larmor frequencies. The first two are due to weak dipolar interaction with the template molecules, while the others reflect interactions with the framework.
- Research Organization:
- Weizmann Inst. of Science, Rehovot, (IL)
- OSTI ID:
- 20000111
- Journal Information:
- Journal of the American Chemical Society, Vol. 121, Issue 25; Other Information: PBD: 30 Jun 1999; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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