- 1 Generalities
- 2 Examples of signal attribute in 1D spectrum
- 3 Attributes
The attributes list the caracteristics of signals found in spectra. List of signal attributes (1D spectra)
Note that they should apear in this order! All labels are optional, the shift value is mandatory.
S= Multiplicity (string) J= Scalar coupling (string) N= number of nuclei (rounded number of atoms) (int) L= Label of the signal (string) E= Integral (crude integrals) (float) I= Intensity (float) W= Width (float) T1= T1 relaxation time in second (float) T2= T2 relaxation time in second (float) Diff= for diffusion rate in m2/s-1 (float)
Examples of signal attribute in 1D spectrum
Chemical shifts are given with four digits after the period (minimum).
Examples of a doublet in 1D 1H spectrum: "4.182 (s, 2H, H-(C3))"
4.1823, S=d, N=2, L=H-(C3) 4.1823, S=d, N=2, L=<> 4.1820-4.1815, S=d, N=2, L=H-(C3)
Examples of a typical signals in 1D 13C spectra: "14.1823 CH2,C(5)"
14.1823, S=2, L=C(5)
Examples of a a negative signal for CH2,C(5) a DEPT 13C spectra
14.1823, S=2, L=C(5), I=-95.12
In case of overlap, second-order effects, use "m". This is meant to be the apparent multiplicity. For example a dd with similar coupling will look as a triplet, can be called "t".
J= Scalar coupling
J= Scalar coupling (unassigned)
Couplings in Hz with two digits after the period separated by the separator.
4.1823, S=dd, N=1, L=a, J=9.30,4.81
indicates a dd with J=9.30 and 4.81 Hz.
4.1823, S=td, N=1, L=a, J=9.30,4.81
means: the first coupling of 9.30 causes a triplet shape and a doublet with J=4.81 Hz.
Following the couplings, labels may be given in parentheses to assign the coupling.
J= Scalar coupling (assigned)
Scalar couplings are given with two digits following the period. For a signal assigned to "a":
4.1823, S=d, N=1, L=a J=9.32(b)
means: J(a,b)=9.32 Hz
4.1823, S=dd, N=1, L=a J=9.32(b),4.80(c)
means: J(a,b)=9.32 Hz and J(a,c)=4.80 Hz
See also, the <NMREDATA_J> tag where assigned coupling should be compiled.
N= number of nuclei
For 1D 1H spectra: 1 for CH, 2 for CH2, N for multiplet, where N is the number of protons in the range
For 1D 13C spectra: 0 for quaternary carbons, N for CHN, where N is the number of protons bound to the carbon
This reflects the value of the integrals, but it is not the value of the integral. The value of the integral can be specified using the "E=" attribute.
E= Signal Integral
E integral (in arbitrary units).
I= Signal intensity
I intensity (in arbitrary units).
W= Signal width
W width of the signal at half height (in Hz).
T1/T2= Relaxation time
Results of relaxation measurements, T1, T2, etc. can be given in seconds as:
4.8000, S=q, E=2, L=a, T1=0.7
Diff= Diffusion rate
Diffusion rates in m2/s-1
4.8000, S=q, E=2, L=a, Diff=1.12e-9
When reading these lines of data, the format is: The first field is a chemical shift (or chemical shift range!!), followed by a number of attributes separated by ", ". Note that we may not require the space (ignore the space!) The structure of each "attribute" is always:
- the name of the attribute (usually in capital letters / no space).
- = (an "equal" sign)
- the value of the attribute. Read and store it as text (in the perspective of writing it later).
They can be directly used as name and value of object properties.
The order of the attributes may change, but we recommend writing them in a certain order... (see above)
Some attributes may be quite complex (in particular the "J" field...)
Note that the J attribute may contain "," meaning that a comma alone is not separating attributes. If the "," is separating J values, what follows the "," is a number (the next J value) if what follows the "," is the next attribute, what follows the "," is alphanumerical and "=".
Keep in mind the possible issue with labels including ",", " ", etc.