perl DBI Oracle UTF8 Charset expected

Question

I am trying to understand what is happening here.

I am using Perl and DBI::Oracle to connect to my Oracle XE database. I want to get UTF encoded characters as return value on my database query. Unfortunately, my expectation is not met. If you take a closer look at the return value this becomes clear ( From line 4). For the umlaut 'ä' I get not c3a4 but e4.

Can someone explain to me why this is happening here

user@pc:~$ cat charset_test.pl
use DBI;
use Data::Dumper;
binmode STDOUT, ":utf8";

my $dbname = "DB:1521/XE";
my $user   = "system";
my $passwd = "password";
$dbh = DBI->connect("dbi:Oracle:$dbname", $user, $passwd);
sub sql{
    my $sql = shift;
    $dbh->{RaiseError} = 1;
    $sth = $dbh->prepare($sql);
    $sth->execute;
    my @dbrow = $sth->fetchrow_array;
    return $dbrow[0];
}

printf( " 0: NLS_LANG           %s \n", $ENV{'NLS_LANG'});
printf( " 1: pack ae            %s \n", unpack( 'H*', "ä" ) );
printf( " 2: sql rawtohex ae    %s \n",               sql("select rawtohex(ae)   from (select UTL_I18N.RAW_TO_CHAR ('c3a4', 'AL32UTF8') as ae from dual)"));
printf( " 3: sql rawtohex('ae') %s \n",               sql("select rawtohex('ä')  from dual") ) ;
printf( " 4: sql 'ae'           %s",    Dumper(       sql("select 'ä'            from dual") ) );
printf( " 5: sql 'ae'           %s \n",               sql("select 'ä'            from dual") ) ;
printf( " 6: pack sql ae        %s \n", unpack( 'H*', sql("select ae             from (select UTL_I18N.RAW_TO_CHAR ('c3a4', 'AL32UTF8') as ae from dual)")));
printf( " 7: pack sql 'ae'      %s \n", unpack ('H*', sql("select 'ä'            from dual") ) );

exit;
user@pc:~$ NLS_LANG=AMERICAN_AMERICA.UTF8 perl charset_test.pl
 0: NLS_LANG           AMERICAN_AMERICA.UTF8
 1: pack ae            c3a4
 2: sql rawtohex ae    C3A4
 3: sql rawtohex('ae') C3A4
 4: sql 'ae'           $VAR1 = "\x{e4}";
 5: sql 'ae'           ä
 6: pack sql ae        e4
 7: pack sql 'ae'      e4