Fig. 5.

Diffusion of atmospheric ¹²C-methane trapped in the plant cells. Before the start of the experiment the plant cell was flushed with methane-free air for 1 h at 60 L h⁻¹. After the initial measurements the flow was 2 L h⁻¹. The water content was reduced by inserting a CaCl₂ scrubber in the flow towards the photoacoustic cell.