Distribution of maximum of i.i.d. exponential random variables

Question

Let ($X_i$) be an i.i.d. sequence of exponentially distributed random variables with common parameter 2. Let $M_n = max_{1 \le i \le n}(X_i)$. Then we have $P(M_n \le x)= \prod_{i=1}^n P(X_i \le x)=(1-e^{-2x})^n$, if $x \ge 0$. My question is: Can we find some normalising contants $a_n,b_n >0$ and real-valued random variable $Z$, s.t. $(M_n-b_n)/a_n \to Z$ in distribution? Try to make $Z$ as easy as possible. Please help, thanks.