Convert Cell Number Reference To String Address

I have something like the following:

If Worksheets("RawData"). Cells(1, nColumn).Value = Worksheets("RawData").Cells(12, 16).Value Then
..do code (I know the cell location of interest at this point)
End If

Then I End up needing To Do something Like the following
ActiveChart.SeriesCollection(1).XValues = _
Worksheets("RawData").Range("L1:N1")

“L1:N1” above is a sample. Given the code above it I have the cell location in question but it is in the format such as .Cells(12,16). That doesn’t do me much good when range wants something like “L1”. I don’t know how to convert that (12,16) to a L16 for example.