title: Recoupling pulse sequences with constant phase increments.
abstract: The paper studies a family of recoupling pulse sequences in magic angle spinning (MAS) solid state NMR, that are characterized by constant phase increments at regular intervals. These pulse sequences can be employed for both homonuclear and heteronuclear recoupling experiments and are robust to dispersion in chemical shifts and rf-inhomogeneity. The homonuclear pulse sequence consists of a building block [Formula: see text] , where ϕ(p)=p(n-1)πn, where n is number of blocks in a rotor period and p=0,1,2,…. The pulse sequence repeats itself every rotor period when n is odd and every two rotor period when n is even. The heteronuclear recoupling pulse sequence consists of a building block [Formula: see text] and [Formula: see text] on channel I and S, where ϕ1(p)=p(2n-3)π2n,ϕ2(p)=p(2n-1)π2n and n is number of blocks in a rotor period. The recoupling pulse sequences mix the z magnetization. Experimental quantification of this method is shown for (13)Cα-(13)CO, homonuclear recoupling in a sample of Glycine and (15)N-(13)Cα, heteronuclear recoupling in Alanine. Application of this method is demonstrated on a sample of tripeptide N-formyl-[U-(13)C,(15)N]- Met-Leu-Phe-OH (MLF).
authors: Department of Electrical Engineering, IIT Bombay, Powai 400076, India. Electronic address: navinkhaneja@gmail.com.
authors: Navin
authors: N
authors: Khaneja
authors: Department of Biosciences and Bioengineering, IIT Bombay, Powai 400076, India.
authors: Ashutosh
authors: A
authors: Kumar
keywords: Broadband homonuclear recoupling; Hartmann-Hahn Matching; Magic angle spinning; Recoupling; rf-inhomogeneity