Time domain baseline correction (NMR)

Here we show how to baseline correct dataset in the time domain before applying FFT.

The example spectra were downloaded from a historical University of Tubingen NMR processing page describing DC-offset correction. That original external page is no longer reliably reachable, so the example below focuses on the SpectroChemPy workflow directly.

[1]:

import spectrochempy as scp

[2]:

# This example uses Bruker NMR data.
#
# Requires the official ``spectrochempy-nmr`` plugin.
# Install with: ``pip install spectrochempy[nmr]``.

[3]:

path = scp.preferences.datadir / "nmrdata" / "bruker" / "tests" / "nmr" / "h3po4"
fid = scp.nmr.read(path, expno=4)
prefs = scp.preferences
prefs.figure.figsize = (7, 3)
_ = fid.plot(show_complex=True)

../../_images/userguide_processing_td_baseline_3_1.png

[4]:

spec = scp.fft(fid)
_ = spec.plot(xlim=(5, -5))

../../_images/userguide_processing_td_baseline_4_0.png

We can see that in the middle of the spectrum there are an artifact (a transmitter spike) due to different DC offset between imaginary.

In SpectroChemPy, for now, we provide a simple kind of dc correction using the dccommand.

[5]:

dc_corrected_fid = fid.dc()
spec = scp.fft(dc_corrected_fid)
_ = spec.plot(xlim=(5, -5))

../../_images/userguide_processing_td_baseline_6_0.png

[6]:

path = scp.preferences.datadir / "nmrdata" / "bruker" / "tests" / "nmr" / "cadmium"
fid2 = scp.nmr.read(path, expno=100)
_ = fid2.plot(show_complex=True)

 WARNING | (UserWarning) (956,)cannot be shaped into(1024,)

../../_images/userguide_processing_td_baseline_7_1.png

[7]:

spec2 = scp.fft(fid2)
_ = spec2.plot()

../../_images/userguide_processing_td_baseline_8_0.png

[8]:

dc_corrected_fid2 = fid2.dc()
spec2 = scp.fft(dc_corrected_fid2)
_ = spec2.plot()

../../_images/userguide_processing_td_baseline_9_0.png