ggplot axis labels with superscript and subscript

super-and-sub-script-labels.R

library(tidyverse)

# using expression() for the text formatting:
ggplot(mtcars,
       aes(disp,
           mpg)) +
geom_point() +
# ~ for spaces, and * for no-space between (unquoted) expressions
ylab(expression(Anthropogenic~SO[4]^{"2-"}~(ngm^-3))) + 
xlab(expression(italic(delta)^13*C[ap]*"‰")) + 
theme_bw(base_size = 16)
 
# using markdown for the text formatting:
library(ggtext)
ggplot(mtcars,
       aes(disp,
           mpg)) +
geom_point() +
ylab("Anthropogenic SO<sub>4</sub><sup>2-</sup> (ngm<sup>-3</sup>)") + 
xlab("*&delta;*<sup>18</sup>O (&permil; VPDB)") + 
theme(axis.title.x = element_markdown(),
      axis.title.y = element_markdown())
theme_bw(base_size = 16) 

# write in Quarto to get per mille unicode symbol to show up on PDF output

```{r}
#| fig.showtext = TRUE

library(showtext)

ggplot(mtcars,
       aes(disp,
           mpg)) +
geom_point() +
ylab(expression(Anthropogenic~SO[4]^{"2-"}~(ngm^-3))) + 
xlab(expression(italic(delta)^13*C[ap]*"‰")) + 
theme_bw(base_size = 16) 
```

This is good thanks for this description. I'm wondering how a new line can be entered in this framework?

@James-Hawkins have you tried the answers here https://stackoverflow.com/a/18237295/1036500 ?