Figure 5
(a) Change of crystal size (black) on applying a humidity gradient (blue) to a CODH crystal. The presumed best crystal state is indicated by a discontinuous change in the crystal dimension in the upward path of the humidity gradient. (b) Control of crystal size by the IR laser. Laser power was regulated to produce a stepwise change in crystal size by −1% in 90 s (downward path) and +2% in 90 s (upward path). After reaching the optimum (a), the humidity was decreased gradually (blue trace) and the laser power (red trace) was regulated to zero, keeping the crystal size constant to preserve the crystal state for X-ray analysis (see text). |