Sympathetically Cooled Molecular Ions

Ryan Carollo, David A. Lane, Alexander Frenett +1 more

Takashi Baba, Izumi Waki

We formulated a model to reproduce the spectral shape of in situ mass spectra of sympathetically cooled molecular ions trapped in a linear radio-frequency-quadrupole. The molecular ions are sympathetically cooled by laser cooled ions. The mass spectrum is obtained by observing fluorescence emitted from the laser-cooled ions as we excite the resonant motion of the sympathetically cooled molecular ions in the trap. The model, which uses a pseudopotential and space-charge approach, reproduces the mass spectra of molecules. The model suggests that the variation of the space-charge density of the laser-cooled ions can produce in-trap kinetic excitation without the loss of the excited ions from the trap.

Stefan Willitsch

Takashi Baba, Izumi Waki

We report an ion/neutral reaction of sympathetically laser-cooled molecular ions. Using laser-cooled fluorescence mass spectrometry, a reaction of about 100 sympathetically cooled H3O+ ions with NH3 were traced at 4 min interval as the reacting ions were kept within a radiofrequency-quadrupole ion trap. To obtain the reaction rate of the reaction molecular dynamical calculation was used to relate the fluorescence mass spectra to the quantity of the molecular ions.

Grahame Vittorini, Craig Robert Clark, Kenneth R. Brown

Martijn A. van Eijkelenborg, M.E.M Storkey, D. M. Segal +1 more

We have trapped and sympathetically cooled the molecular ions ${\mathrm{HCO}}^{+}$ and ${\mathrm{N}}_{2}{\mathrm{H}}^{+}$ in a Penning trap. Through their Coulomb interaction with laser-cooled ${\mathrm{Mg}}^{+}$ ions the molecules were sympathetically cooled to cryogenic temperatures. We identify the molecules through a measurement of their characteristic mass-dependent breathing mode frequencies. From a measurement of the temperature of the ${\mathrm{Mg}}^{+}$ ions we estimate that the final temperature of the sympathetically cooled molecules is 4 K.