SPIN-ECHO STUDIES OF CHEMICAL EXCHANGE. II. CLOSED FORMULAE FOR THE T-2 OF TWO SITES.
Abstract
Closed expressions are derived for the decay in amplitude of successive echoes in nuclear magnetic resonance experiments for systems with two exchanging sites having different resonance frequencies but equal transverse relaxation times 'in the absence of exchange.' The decay is found to be the sum of two exponential terms and two 'pseudo-exponential' terms; the absolute values of the latter decay exponentially but the sign alternates from one echo to the next. For the case of two equally populated sites the decay simplifies to the sum of just one exponential and one 'pseudo-exponential' term. In most cases of experimental importance a single exponential term is much larger than the rest and adequately describes the decay in echo amplitude. An iterative computer procedure is described which uses the expressions to extract information about the system from measurements of the apparent decay time constant as a function of 180 degree pulse separation. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 29, 1964
- Accession Number
- AD0608708
Entities
People
- Adam Allerhand
- Herbert S. Gutowsky
Organizations
- University of Illinois Urbana–Champaign