?vector
X <- vector(mode="character", length=10)
This will give you empty strings which get printed as two adjacent double quotes, but be aware that there are no double-quote characters in the values themselves. That's just a side-effect of how print.default displays the values. They can be indexed by location. The number of characters will not be restricted, so if you were expecting to get 10 character element you will be disappointed.
> X[5] <- "character element in 5th position"
> X
[1] "" ""
[3] "" ""
[5] "character element in 5th position" ""
[7] "" ""
[9] "" ""
> nchar(X)
[1] 0 0 0 0 33 0 0 0 0 0
> length(X)
[1] 10