Acetone mobility in zeolite cages with new features in the deuteron NMR spectra and relaxation
PBN-AR
Instytucja
Instytut Fizyki Jądrowej im. Henryka Niewodniczańskiego Polskiej Akademii Nauk
Informacje podstawowe
Główny język publikacji
en
Czasopismo
SOLID STATE NUCLEAR MAGNETIC RESONANCE (30pkt w roku publikacji)
ISSN
0926-2040
EISSN
Wydawca
DOI
URL
Rok publikacji
2018
Numer zeszytu
Strony od-do
7-15
Numer tomu
93
Identyfikator DOI
Liczba arkuszy
Autorzy
(liczba autorów: 4)
Pozostali autorzy
+ 2
Słowa kluczowe
en
Non-exponential NMR relaxation
Activation energy distribution
Decreasing activation energy
Rotational tunnelling
Acetone in zeolite
Deuteron NMR spectra
Molecular mobility
Methyl group
Streszczenia
Język
en
Treść
We studied deuteron NMR spectra and spin−lattice relaxation of deuterated acetone-d6, adsorbed into zeolites NaX (1.3) and NaY(2.4) at 100% coverage of sodium cations. At temperatures roughly below 160 K the deuterons are localized and their NMR characteristics are determined by CD3 rotation and rotational oscillations of acetone molecules. In NaX the CD3 rotation and rotational oscillations about the twofold axis of acetone dominate the spectra below 100 K, while above it oscillations also about other axes become important. In NaY dominant features are related to methyl tunnelling and to a smaller extent to rigid acetones, before the rotational oscillations about twofold axis start to prevail above 40 K. The analysis of the strongly non-exponential magnetization recovery was done by applying the recently introduced method (Ylinen et al., 2015 [12]), improved here to take into account the limited fast recovery at the level crossings, 10% at and 28% at . At first the experimental recovery is fitted by three exponentials with adjustable weights and decay rates. Then these quantities are calculated from activation energy distributions and known expressions for the deuteron relaxation rate. In NaY two distinctly separate activation energy distributions were needed, the dominant one being very broad. The use of three distributions, two of them covering practically the same energies as the broad one, lead to a somewhat better agreement with experiment. In general the theoretical results agree with experiment within experimental scatter. As the final result the mean activation energies and widths are obtained for activation energy distributions.
Cechy publikacji
peer-reviewed
original-article
Inne
System-identifier
30231/2018
CrossrefMetadata from Crossref logo
Cytowania
Liczba prac cytujących tę pracę
Brak danych
Referencje
Liczba prac cytowanych przez tę pracę
Brak danych