Relaxation of AB Spin Systems in Stimulated-Echo Spectroscopy

✍ Scribed by Klaus Straubinger; Fritz Schick; Otto Lutz

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 233 KB
• Volume: 109
• Category: Article
• ISSN: 1064-1866
• DOI: 10.1006/jmrb.1995.9998

✦ Synopsis

The behavior of the strongly coupled AB spin system during as analytical functions, incorporating all parameters as varithe STEAM (stimulated echo acquisition mode) sequence was calables. It is possible to evaluate how changing parameters culated analytically. Relaxation during the TM interval, in which (chemical-shift difference, coupling constant, sequence timlongitudinal magnetization and zero-quantum coherences (ZQCs) ing, etc.) affects spectra and signal intensities. occur, was accounted for by following the course of the different density-matrix terms. The result allows one to determine sequence THEORY timings to provide high signal intensities or signals resulting from certain coherences. Theoretically calculated spectra can be gener-Basics and Software ated, using an analytical function. Series of proton spectra were recorded from a 0.1 m aqueous solution of citrate on a 1.5 T whole-

The time evolution of strongly coupled spin systems can body imager at 22ЊC. Spectra series with constant echo time TE be calculated by density-operator theory (10,11). The mawere used to evaluate the longitudinal relaxation time T 1 as well trix form of the spin operators (12, 13) was used, because as the zero-quantum relaxation time T ZQ by fitting the theoretically it was found to be better adapted for treatment by computer predicted curve to the experimental data. The evaluated proton algebra than the AB-system product-operator formalism relaxation times T 1 and T ZQ in citrate differ strongly: T 1 Å 770 (14). The resulting density matrix was converted to the ms, T ZQ Å 1300 ms.