Return the character associated with the specified Ascii code in R

Good afternoon,

I'm trying to create a cartesian product in R with the letters of the alphabet.

What I'm actually trying is this:

First I create a matrix with the letters

a <- as.matrix(seq(97,122,by=1))

Then I create a data frame with 2 columns with all the combinations

b <- expand.grid(a, a)

Finally I combine the 2 columns

apply(b,1,paste,collapse=" ")

The problem I have is that I can't find a way to transform those "decimals" to its Ascii character.

I have tried several things like rawToChar and gsub unsuccessfully.

Can somebody point me in the right direction?

Thanks