IR NMR MS Spectroscopy

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Spectroscopy is the study of quantized interaction of energy (typically electromagnetic energy) with matter. The derivation of structural information from spectroscopic data is an important part of chemistry. A common way to simplify this process is to combine information from major spectroscopic and spectrometric techniques as NMR 1,IR2 and MS 3. 1) NMR - Nuclear Magnetic Resonance Spectroscopy
2) IR - Infrared Spectroscopy
3) MS - Mass Spectrometry

Butanone MS, IR, 1H-NMR and 13C-NMR sample spectra

Fig.1 MS-spectra containing a CH3C=O fragment(43 m/e)

MS Specroscopy

Fig.2 IR-spectra with a strong C=O absorbation (1705 cm-1)

IR Spectroscopy

Fig.3 1H-NMR spectra indicating a methyl-methylene coupling

HNMR Specroscopy

Fig.4 13C-NMR spectra. Off resonance decoupled (upper) and proton decoupled with a 13C line in an typical area (209ppm) for C=O.

CNMR Specroscopy

Mass Spectrometry

Show isotope formula : Show C[12]2H[1]6 (isotope formula) instead of C2H6 .
Text field (upper): Fragment masses separated by spaces
+/-me- : Accuracy for the search/iteration in electron masses (1840 me- = 1 mn).
Iterate -> : A method in which finds solutions to MS problems by the use of selected isotopes. CHEMIX will try to match input masses by combining masses of all the selected isotopes and their index values (iterative limits). If to many isotope combinations matches the input data, a dotted line (...) will be seen. This problem can be avoided by a reduction of the (+/-me-) value. By not selecting Iterate, CHEMIX will perform a search in the MS-data file.

IR and NMR Spectroscopy (H[1] and C[13])

Text fields : IR wave numbers (cm-1) or NMR ppm values.

Interpretation of parameters and results

(1/1), (1/2), (2/3).... (hits/potential hits)
(1/1) = 1 hit of potential 1 hit (Hit% = 100)
(1/2) = 1 hit of potential 2 hits (Hit% = 50)
(2/2) = 2 hits of potential 2 hits (Hit% = 100)
(5/8) = 5 hits of potential 8 hits (Hit% = 5/8*100 = 62.5)

LPHV (Lowest Potential Hit Value) represent the lowest accepted denominator in a fraction (1/LPHV). The result of increasing LPHV from 1 -> 2 (at least two resonance/absorption areas must be present in data file), is that even a 100 hit% as (1/1) will be ignored as a valid hit.


Save experiment : MS(+/-me- + selected isotopes + spectral data) + IR/NMR spectral data.
The default settings for Spectroscopy can be changed and saved by the use of Settings -> Save settings

CHEMIX School - Spectroscopy assignment

Spectroscopy assignment

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