Function that converts transmittance (fraction) into \(\log_{10}\)-based absorbance (a.u.).
T2A(x, action, byref, clean, ...)# S3 method for default
T2A(x, action = NULL, byref = FALSE, ...)
# S3 method for numeric
T2A(x, action = NULL, byref = FALSE, clean = TRUE, ...)
# S3 method for filter_spct
T2A(x, action = "add", byref = FALSE, clean = TRUE, strict.A = FALSE, ...)
# S3 method for filter_mspct
T2A(
x,
action = "add",
byref = FALSE,
clean = TRUE,
strict.A = TRUE,
...,
.parallel = FALSE,
.paropts = NULL
)
A copy of x
with a column A
added and other columns
possibly deleted except for w.length
. If action = "replace"
,
in all cases, the additional columns are removed, even if no column needs
to be added.
an R object.
character Allowed values "replace"
and "add"
.
logical indicating if new object will be created by reference
or by copy of x
.
logical replace off-boundary values before conversion
not used in current version
logical Attempt to compute a true internal absorbance even
if "total"
transmittance is stored in x
.
if TRUE
, apply function in parallel, using parallel backend
provided by foreach
a list of additional options passed into the foreach function when parallel computation is enabled. This is important if (for example) your code relies on external data or packages: use the .export and .packages arguments to supply them so that all cluster nodes have the correct environment set up for computing.
T2A(default)
: Default method for generic function
T2A(numeric)
: Method for numeric vectors
T2A(filter_spct)
: Method for filter spectra
T2A(filter_mspct)
: Method for collections of filter spectra
Absorbance, \(A\), is frequently used in chemistry as it is linearly related to the concentration of a solute dissolved in a solvent.
$$A = -\log_{10} \tau$$
where, \(A\) absorbance and \(\tau\) is internal transmittance. By
default, if total transmittance, \(T\), is stored in x
, the
returned value computed as
$$A = -\log_{10} T$$
is not strictly absorbance. In this case and in cases when the measured light attenuation is the result of scattering, or when part of measured light is re-emitted after absorption the use of attenuance is the IUPAC-recommended name for this quantity.
If strict.A = TRUE
is passed in the call and total
transmittance, \(T\), and total
reflectance, \(\rho\), are both available, absorbance is computed as:
$$A = -\log_{10} (T - \rho) / (1 - \rho)$$
where \(\rho\) can be either spectral total reflectance stored in x
as data or a single approximate Rfr.constant
value stored as part
of the metadata.
Other quantity conversion functions:
A2T()
,
Afr2T()
,
T2Afr()
,
any2T()
,
as_quantum()
,
e2q()
,
e2qmol_multipliers()
,
e2quantum_multipliers()
,
q2e()