Nuclei, coherences and Xi ratios

Nuclei

NMRTools defines the nuclei below as instances of Nucleus. A nucleus can also be looked up from a string with nucleus, e.g. nucleus("15N"). The columns give the values returned by each function for nucleus n.

Nucleus	Spin: `spin(n)`	γ (rad s⁻¹ T⁻¹): `gyromagneticratio(n)`	Xi ratio, DSS (aqueous): `xi_ratio(n)`	Xi ratio, TMS (organic): `xi_ratio(n; aqueous=false)`
`H1`	1//2	2.6752218744e8	1.0	1.0
`H2`	1	4.1065e7	0.1535060886	0.1535060886
`C12`	0	–	–	–
`C13`	1//2	6.72828e7	0.25144953	0.2514502
`N14`	1	1.9331e7	–	–
`N15`	1//2	-2.7116e7	0.101329118	0.101329118
`F19`	1//2	2.51815e8	0.94094011	0.94094011
`P31`	1//2	1.08291e8	0.40480742	0.40480742

Xi ratios are the IUPAC ratios of each nucleus's reference frequency to that of ¹H in the reference compound, used for indirect referencing (see Reference chemical shifts). DSS is the reference for aqueous samples and TMS for organic solvents.

Coherences

Coherences are described by SQ (single quantum, on one nucleus) and MQ (multiple quantum, a combination of nuclei with coherence orders), both subtypes of Coherence. coherenceorder gives the total order:

julia> coherenceorder(SQ(H1))1
julia> coherenceorder(MQ(((H1, 1), (C13, 1))))     # double quantum2
julia> coherenceorder(MQ(((H1, 1), (C13, -1))))    # zero quantum0

gyromagneticratio of a coherence is the sum over its nuclei, weighted by their orders:

julia> gyromagneticratio(MQ(((H1, 1), (C13, 1))))3.3480498744e8