Nuclei and coherences

Nucleus

Enumeration of common nuclei associated with biomolecular NMR. Nuclei are named e.g. H1, C13.

Defined nuclei: H1, H2, C12, C13, N14, N15, F19, P31.

See also spin, gyromagneticratio, Coherence.

nucleus(label::AbstractString) -> Nucleus

Parse a nucleus from a string label, returning the corresponding Nucleus enum value.

The function accepts common NMR nucleus notation formats:

• Mass number followed by element symbol: "1H", "13C", "15N", "19F", "31P"
• Element symbol followed by mass number: "H1", "C13", "N15", "F19", "P31"

Examples

julia> nucleus("19F")
F19::Nucleus = 6

julia> nucleus("H1")
H1::Nucleus = 0

julia> nucleus("7Li")
ERROR: ArgumentError: Unknown nucleus: 7Li
[...]

Throws ArgumentError if the nucleus is not recognised or not defined in the Nucleus enum.

spin(n::Nucleus)

Return the spin quantum number of nucleus n, or nothing if not defined.

Examples

julia> spin(H1)
1//2

See also Coherence.

gyromagneticratio(n::Nucleus)
gyromagneticratio(c::Coherence)

Return the gyromagnetic ratio in Hz/T of a nucleus, or calculate the effective gyromagnetic ratio of a coherence. This is equal to the product of the individual gyromagnetic ratios with their coherence orders.

Returns nothing if not defined.

Examples

julia> gyromagneticratio(H1)
2.6752218744e8

julia> gyromagneticratio(SQ(H1))
2.6752218744e8

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

julia> gyromagneticratio(MQ(((H1,0),)))
0.0

See also Nucleus, Coherence.

xi_ratio(n::Nucleus; aqueous=true)

Return the Xi ratio for nucleus n, used for indirect chemical shift referencing.

The Xi ratio is defined as the ratio of the reference frequency of nucleus X to the 1H reference frequency (TMS or DSS). This enables indirect referencing of heteronuclear dimensions from a single 1H reference.

Arguments

• n::Nucleus: The nucleus for which to retrieve the Xi ratio
• aqueous=true: If true, use DSS-based ratios (aqueous solutions). If false, use TMS-based ratios (organic solvents).

Returns

• The Xi ratio as a Float64, or nothing if not defined for this nucleus.

Examples

julia> xi_ratio(C13)
0.25144953

julia> xi_ratio(C13; aqueous=true)
0.25144953

julia> xi_ratio(C13; aqueous=false)
0.2514502

julia> xi_ratio(N15)
0.101329118

References

• Markley et al., 1998, Pure Appl. Chem. 70, 117-142
• Wishart et al., 1995, J. Biomol. NMR 6, 135-140
• Maurer and Kalbitzer, 1996, J. Magn. Reson. B113, 177-178
• IUPAC recommendations 2001/2008

See also reference, Nucleus.

Coherence

Abstract supertype for representing coherences.

See also SQ, MQ.

SQ(nucleus::Nucleus, label=="")

Representation of a single quantum coherence on a given nucleus.

See also Nucleus, MQ.

MQ(coherences, label=="")

Representation of a multiple-quantum coherence. Coherences are specified as a tuple of tuples, of the form (nucleus, coherenceorder)

Examples

julia> MQ(((H1,1), (C13,-1)), "ZQ")
MQ(((H1, 1), (C13, -1)), "ZQ")

julia> MQ(((H1,3), (C13,1)), "QQ")
MQ(((H1, 3), (C13, 1)), "QQ")

See also Nucleus, SQ.

coherenceorder(coherence)

Calculate the total coherence order.

Examples

julia> coherenceorder(SQ(H1))
1

julia> coherenceorder(MQ(((H1,1),(C13,1))))
2

julia> coherenceorder(MQ(((H1,1),(C13,-1))))
0

julia> coherenceorder(MQ(((H1,3),(C13,1))))
4

julia> coherenceorder(MQ(((H1,0),)))
0

See also Nucleus, SQ, MQ.

NMRToolsError(message)

An error arising in NMRTools.