excitation          
noun [ U ] uk/ˌek.saɪˈteɪ.ʃən/ us/ˌek.saɪˈteɪ.ʃən/
 science specialized刺激;激励 
the process of making something, for example a particle or a cell, more active
  The absorbed X-rays cause excitation of the electrons in the atoms of a crystal. 吸收的X射线引起晶体原子中电子的激发。 
  (性)兴奋
the process of becoming sexually excited
  sexual excitation 性兴奋