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Calculation of \(g\)-factor ("Position") from the 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 by the eval_peakPick_Spec. If positive and negative derivative intensities of the spectral line are similar and their distances from the middle point of the spectrum are close, 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/are used for the \(g\)-value calculation. If instead of one central two \(B\)-values/lines appear, the function automatically calculates the middle point between both.

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(ies).

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_kinR_Eyring_GHS(), 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_file = 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