Lists the lines of the selected atoms and ions that are expected to be the strongest in a plasma at a given temperature, from the NIST Atomic Spectra Database, to help identify the emission lines of a spectrum.
Usage
libs_lines(
species,
wavelength = c(200, 900),
temperature = 10000,
top = 20,
min_relative = 0,
timeout = 120
)Arguments
- species
A character vector of emitters in spectroscopic notation, such as
c("Ca I", "Ca II", "Mg I").- wavelength
A numeric vector of length 2: the wavelength range, in nm. Default is 200 to 900 nm.
- temperature
The plasma temperature, in K. Default is 10000.
- top
The maximum number of lines kept per species. Default is 20.
- min_relative
The minimum relative intensity of the lines kept, between 0 and 1. Default is 0.
- timeout
The download timeout, in seconds. Default is 120.
Value
A tibble with one row per line, sorted by wavelength, and
columns species, element, stage (1 for neutral atoms, 2 for
singly charged ions, ...), wavelength (nm), relative_intensity,
Aki, Ek, gk, accuracy, lower and upper. Species without
lines in the range contribute no rows.
Details
For each species, the lines with a transition probability are retrieved
with nist_lines() (and cached for the R session). Their relative
intensities in a plasma in local thermodynamic equilibrium at
temperature \(T\) are
$$I \propto \frac{g_k A_{ki}}{\lambda} \exp\left(-\frac{E_k}{k_B T}\right)$$
normalized to the strongest line of the species in the range. The
intensities are relative within each species: comparing species would
need their concentrations and, between ionization stages, the Saha
equation. Self-absorption, which weakens resonance lines, is ignored.
The top strongest lines of each species with a relative intensity of
at least min_relative are kept. plot_lines() overlays them on a
spectrum, and line_finder() does so interactively.
Examples
# \donttest{
# needs an internet connection
lines <- try(libs_lines(c("Ca I", "Ca II"), wavelength = c(390, 450), top = 5))
if (!inherits(lines, "try-error")) lines
#> # A tibble: 10 × 11
#> species element stage wavelength relative_intensity Aki Ek gk
#> <chr> <chr> <int> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 Ca II Ca 2 393. 1 147000000 3.15 4
#> 2 Ca II Ca 2 397. 0.487 140000000 3.12 2
#> 3 Ca II Ca 2 410. 0.0000123 9900000 10.5 4
#> 4 Ca II Ca 2 411. 0.0000224 12000000 10.5 6
#> 5 Ca II Ca 2 422. 0.00000564 8500000 10.5 2
#> 6 Ca I Ca 1 423. 1 218000000 2.93 3
#> 7 Ca I Ca 1 430. 0.120 136000000 4.78 5
#> 8 Ca I Ca 1 432. 0.0394 74000000 4.77 3
#> 9 Ca I Ca 1 443. 0.0642 67000000 4.68 5
#> 10 Ca I Ca 1 445. 0.116 87000000 4.68 7
#> # ℹ 3 more variables: accuracy <chr>, lower <chr>, upper <chr>
# }