# tth_transform: Transform a two theta axis between wavelengths In benmbutler/powdR: Full Pattern Summation of X-Ray Powder Diffraction Data

## Description

`tth_transform` converts the two theta axis from one wavelength to another via Bragg's law. Use this function with caution if intending the apply `fps()` or `afps()` to wavelength transformed samples or libraries because background signals can vary with wavelength which may therefore affect the quality of the fit.

## Usage

 `1` ```tth_transform(tth, from, to) ```

## Arguments

 `tth` the 2theta vector to be transformed `from` numeric value defining the wavelength (Angstroms) to transform from `to` numeric value defining the wavelength (Angstroms) to transform to

## Value

a transformed 2theta vector

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25``` ```data(soils) sandstone2 <- soils\$sandstone #Convert from Cu (1.54056 Angstroms) to Co (1.78897 Angstroms) sandstone2\$tth <- tth_transform(sandstone2\$tth, from = 1.54056, to = 1.78897) #plot the change plot(soils\$sandstone, type = "l", xlim = c(0, 85)) lines(sandstone2, col = "red") #Alternatively convert the 2theta axis of a library data(minerals) minerals2 <- minerals minerals2\$tth <- tth_transform(minerals2\$tth, from = 1.54056, to = 1.78897) #Plot the difference plot(x = minerals\$tth, y = minerals\$xrd\$QUA.1, type = "l", xlim = c(0, 85)) lines(x = minerals2\$tth, y = minerals2\$xrd\$QUA.1, col = "red") ```

benmbutler/powdR documentation built on Sept. 16, 2020, 5:03 a.m.