1. Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011, USA
2. Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011, USA
3. MTEC Photoacoustics Inc., 3507 Oakland Street, Ames, Iowa 50014, USA
4. Ames Laboratory-USDOE, Ames, Iowa 50011, USA