Measurement of the 202 ← 101 rotational ground state transition with the IR-mm-wave double resonance technique at 11 K. The energy level diagram (inset) explains the double resonance method: with the IR light held in resonance (OPO; long green arrow) at 3029.6352 cm-1, more than 5100 CH signal counts are obtained. When the submm-wave source (THz, small red arrow) is tuned into resonance, additional CH2D+ ions are pumped into the 202 rotational level, leading to an increase of the signal by about 500 counts. In this example, the submm-wave source has been tuned up and down six times, stepping 10 kHz after each 1 s trapping cycle. A Gaussian fit of the seen signal gives a centre frequency of 534 280.0217(24) MHz and a kinetic temperature of about 30 K. Eight such measurements lead to the final value given in Table 1.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.