Method and sample spinning apparatus for measuring the NMR spectrum of an orientationally disordered sample

Claim 1

A method for measuring an NMR spectrum of a sample comprising the steps of generating a magnetic field in said sample; causing said sample to spin about a sample axis inclined at a first angle, Θ 1 , with respect to the direction of said magnetic field; exciting said sample with a first electromagnetic pulse; allowing the magnetization of said sample to precess for a first time interval, T 1 , after the cessation of said first electromagnetic pulse; exciting said sample with a second electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse; causing said sample axis to be inclined at a second angle, Θ 2 , with respect to the direction of said magnetic field; exciting said sample with a third electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse; allowing the magnetization of said sample to precess for a second time interval, T 2 , after the cessation of said third electromagnetic pulse; and detecting the magnitude and phase of the electromagnetic energy emanating from said sample: wherein Θ 1 , Θ 2 , T 1 , and T 2 are chosen such that T 1 P n (cos(Θ 1 )+T 2 P n (cos(Θ 2 )=0 and T 1 P m (cos(Θ 1 )+T 2 P m (cos(Θ 2 )=0, where P n and P m are Legendre polynomials of rank n and m, respectively, and n is not equal to m.

Claim 2

A method for measuring an NMR spectrum of a sample comprising the steps of generating a magnetic field in said sample; causing said sample to spin about a sample axis inclined at a first angle, Θ 1 , with respect to the direction of said magnetic field; exciting said sample with a first electromagnetic pulse; allowing the magnetization of said sample to precess for a first time interval, T 1 , after the cessation of said first electromagnetic pulse; exciting said sample with a second electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse; causing said sample axis to be inclined at a second angle, Θ 2 , with respect to the direction of said magnetic field; exciting said sample with a third electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse; allowing the magnetization of said sample to precess for a second time interval, T 2 , after the cessation of said third electromagnetic pulse; and detecting the magnitude and phase of the electromagnetic energy emanating from said sample: wherein Θ 1 , Θ 2 , T 1 , and T 2 are chosen such that T 1 P n (cos(Θ 1 )+T 2 P n (cos(Θ 2 )=0 and T 1 P m (cos(Θ 1 )+T 2 P m (cos(Θ 2 )=0, where P n and P m are Legendre polynomials of rank n and m, respectively, and n is not equal to m.

Claim 5

An apparatus for measuring an NMR spectrum of a sample in a magnetic field comprising: means for causing said sample to spin about a sample axis inclined at a first angle, Θ 1 , with respect to the direction of said magnetic field; means for causing said sample axis to be inclined at a second angle, Θ 2 , with respect to the direction of said magnetic field; electromagnetic exciting means for exciting said sample with first, second and third electromagnetic pulses, said second electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse, said second electromagnetic pulse being applied at a time T 1 after the cessation of said first electromagnetic pulse; said third electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse, said third electromagnetic pulse being applied after said sample axis has been inclined at Θ 2 with respect to the direction of said magnetic field; and means for detecting the magnitude and phase of the electromagnetic energy emanating from said sample at a time T 2 after the cessation of said third electromagnetic pulse; wherein Θ 1 , Θ 2 , T 1 , and T 2 are chosen such that T 1 P n (cos(Θ 1 )+T 2 P n (cos(Θ 2 )=0 and T 1 P m (cos(Θ 1 )+T 2 P m (cos(Θ 2 )=0, where P n and P m are Legendre polynomials of rank n and m, respectively, and n is not equal to m.

Claim 6

An apparatus for measuring an NMR spectrum of a sample in a magnetic field comprising: means for causing said sample to spin about a sample axis inclined at a first angle, Θ 1 , with respect to the direction of said magnetic field; means for causing said sample axis to be inclined at a second angle, Θ 2 , with respect to the direction of said magnetic field; electromagnetic exciting means for exciting said sample with first, second and third electromagnetic pulses, said second electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse, said second electromagnetic pulse being applied at a time T 1 after the cessation of said first electromagnetic pulse; said third electromagnetic pulse having a predetermined phase relative to said first electromagnetic pulse, said third electromagnetic pulse being applied after said sample axis has been inclined at Θ 2 with respect to the direction of said magnetic field; and means for detecting the magnitude and phase of the electromagnetic energy emanating from said sample at a time T 2 after the cessation of said third electromagnetic pulse; wherein Θ 1 , Θ 2 , T 1 , and T 2 are chosen such that T 1 P n (cos(Θ 1 )+T 2 P n (cos(Θ 2 )=0 and T 1 P m (cos(Θ 1 )+T 2 P m (cos(Θ 2 )=0, where P n and P m are Legendre polynomials of rank n and m, respectively, and n is not equal to m.