双曲线\(C： \dfrac {x^{2}}{a^{2}}- \dfrac {y^{2}}{b^{2}}=1(a > 0,b > 0)\)的左、右焦点分别为\(F _{1}\)，\(F _{2}\)，\(M\)为\(C\)的渐近线上一点，直线\(F _{2} M\)交\(C\)于点\(N\)，且\( \overrightarrow {F_{2}M}\cdot \overrightarrow {OM}=0\)，\( \overrightarrow {F_{2}M}= \dfrac {3}{2} \overrightarrow {F_{2}N} (O\)为坐标原点\()\)，则双曲线\(C\)的离心率为\((\:\:\:\:)\)