open my $fh, ">:raw:encoding(UTF-16LE):crlf", "err.utf16" or die;
print $fh "h\x{00e4}llo\n";

$ od -tx1 -An err.utf16
 68 00 00 00 6c 00 6c 00 6f 00 0d 00 0a 00
       ^^
       wrong