A combined heating cooling stage for cluster thermalization in the gas phase

Abstract

We report on the design and performance of a combined heating/cooling stage for the thermalization of clusters in a gas phase time-of-flight mass spectrometer. With this setup the cluster temperature can sensitively be adjusted within the range from 100 up to 800 K and higher. The unique combination of a heating stage with a subsequent cooling stage allows us to perform thermodynamic investigations on clusters at very high temperatures without quality losses in the spectra due to delayed fragmentation in the drift tube of the mass spectrometer. The performance of the setup is demonstrated by the example of (C 60 ) n clusters.

Experimental and Theoretical Investigations of the Thermodynamic Stability of Ba−C60 and K−C60 Compound Clusters

“…The clusters are formed within a noble gas condensation cell and transported through the system to the detector by a jet of He atoms. A novel heating/cooling stage allowing an adjustment to the cluster temperature between 150 and 1800 K is mounted directly after the cluster source . Inside the stage the clusters thermalize with the He bath by collisions, thus assuming the desired temperature.…”

“…A novel heating/cooling stage allowing an adjustment to the cluster temperature between 150 and 1800 K is mounted directly after the cluster source. 34 Inside the stage the clusters thermalize with the He bath by collisions, thus assuming the desired temperature. The dwell time of the clusters inside the heating stage can be varied between 0.5 and 1 ms by controlling the He pressure inside the source.…”

“…Details of the experiment have been published elsewhere. 34,36 Computational Methods. The computations were performed with the Amsterdam Density Functional (ADF) 18,37 and the Turbomole 38 program packages.…”

Magic alkali-fullerene compound clusters of extreme thermal stability

“…Details of the experiment are published elsewhere. 12,15 Using this setup the thermal stability of small fullerene clusters was investigated. The peak intensity of ͑C 60 ͒ m clusters in the mass spectra was recorded in the temperature range between T = 150 K to 500 K ͑Ref.…”

“…A novel heating/cooling stage allowing to adjust the cluster temperature between 150 K and 1800 K is mounted directly after the cluster source. 15 Inside the stage the clusters thermalize with the He bath by collisions, thus assuming the desired temperature. The dwell time of the clusters inside the heating stage can be varied between 0.5 ms and 1 ms by controlling the He pressure inside the source.…”