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Calculation of \(g\)-factor ("Position") from EPR Spectrum/Data

Source: R/eval_gFactors.R
eval_gFactor_Spec.Rd

Calculation of g-value according to fundamental formula, see eval_gFactor. \(g\)-related magnetic flux density (like \(B_{\text{iso}}\) or \(B_{\text{center}}\)) is directly taken from the EPR spectrum. If positive and negative derivative intensities of the spectral line are similar and their distance from the middle point of the spectrum equals, the \(B_{\text{iso}}\) should be considered. Otherwise, the \(B_{\text{center}}\) must be taken into account. In case of integrated EPR spectrum/data, the \(B_{\text{max}}\) is used for the \(g\)-value calculation.

Usage

eval_gFactor_Spec(
  data.spectr,
  nu.GHz,
  B.unit = "G",
  B = "B_G",
  Intensity = "dIepr_over_dB",
  lineSpecs.form = "derivative",
  Blim = NULL,
  iso = TRUE
)

Arguments

data.spectr

Spectrum data frame object where the magnetic flux density (in mT or G or T) column can be labeled as Field or B_G and that of the derivative intensity as dIepr_over_dB or single integrated intensity like Integrated_Intensity (index column might be included as well).

nu.GHz

Numeric value, microwave frequency in GHz.

B.unit

Character string, denoting the magnetic flux density unit e.g. B.unit = "G" (gauss, default) or B.unit = "mT"/"T" (millitesla/tesla).

B

Character string, pointing to magnetic flux density column of the EPR spectrum data frame data.spectr either in "millitesla"/"tesla" or in "gauss", that is B = "B_mT" (default) or B = "B_G"/B = "T" or B = "Bsim_G" to include simulated EPR spectra as well.

Intensity

Character string, pointing to intensity column if other than dIepr_over_dB name/label is used (e.g. for simulated spectra), default: Intesity = "dIepr_over_dB"

lineSpecs.form

Character string, describing either "derivative" (default) or "integrated" (i.e. "absorption" which can be used as well) line form of the analyzed EPR spectrum/data.

Blim

Numeric vector, magnetic flux density in mT/G/T corresponding to lower and upper limit of the selected \(B\)-region, such as Blim = c(3495.4,3595.4). Default: Blim = NULL (corresponding to the entire \(B\)-range of the EPR spectrum).

iso

Logical, whether to calculate the \(g\)-factor from the \(B\)-value corresponding to that between the min. and max. derivative intensities (dIepr_over_dB, that is \(g_{\text{iso}}\) (this is the default one: iso = TRUE), or by finding the \(B\)-value corresponding to dIepr_over_dB = 0 (close to zero, which is iso = FALSE). For the lineSpecs.form = "integrated" (or absorptiion), the iso is related to magnetic flux density with max. intensity.

Value

Numeric \(g_{\text{iso}}\)-value ('iso' = 'isotropic') or \(g_{\text{center}}\), from the EPR spectrum, according to \((h\,\nu)/(\mu_{\text{B}}\,B)\).

See also

Other Evaluations: eval_DeltaXpp_Spec(), eval_FWHMx_Spec(), eval_extremeX_Spec(), eval_gFactor(), eval_interval_cnfd_tVec(), eval_nu_ENDOR(), eval_peakPick_Spec()

Examples

## load package built-in EPR spectral data example:
data.file.path <-
  load_data_example(file = "TMPD_specelchem_accu_b.asc")
data.epr <-
  readEPR_Exp_Specs(path_to_ASC = data.file.path,
                    col.names = c("B_G",
                                  "dIepr_over_dB"),
                    qValue = 3500,
                    origin = "winepr")
#
## g_iso calculation from EPR spectrum/data:
eval_gFactor_Spec(data.spectr = data.epr,
                  nu.GHz = 9.814155,
                  B.unit = "mT",
                  B = "B_mT",
                  Blim = c(349.677, 350.457))
#> [1] 2.00304