Various PHP Escape Sequences for Special Characters in Double Quoted String

\n  linefeed (LF or 0x0A (10) in ASCII)
\r  carriage return (CR or 0x0D (13) in ASCII)
\t  horizontal tab (HT or 0x09 (9) in ASCII)
\v  vertical tab (VT or 0x0B (11) in ASCII) (since PHP 5.2.5)
\e  escape (ESC or 0x1B (27) in ASCII) (since PHP 5.4.0)
\f  form feed (FF or 0x0C (12) in ASCII) (since PHP 5.2.5)
\\  backslash
\$  dollar sign
\"  double-quote

Here's a PHP docs article in the context of regexes about Escape Sequences in PHP