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SUMMARY:Development of a stable measurement system for Radio-Frequency stu
 dies of muonium reactivity with metal nanoparticles and surface-adsorbed m
 olecules in mesoporous hosts
DTSTART;VALUE=DATE-TIME:20220901T164000Z
DTEND;VALUE=DATE-TIME:20220901T170000Z
DTSTAMP;VALUE=DATE-TIME:20220826T122009Z
UID:indico-contribution-3786@indico.stfc.ac.uk
DESCRIPTION:Speakers: Stephen Cottrell (STFC)\nWe have recently begun an i
 nvestigation of paramagnetic (free-radical) final states formed on metal n
 anoparticles by muonium reactivity with surface-adsorbed molecules. The na
 noparticles are incorporated into mesoporous silica\, facilitating specifi
 c reaction steps in the silica host that involve H-atom transfer reactions
  important to studies in heterogeneous catalysis. Radio-frequency (RF) met
 hods are an essential tool for characterising final state species in these
  systems\, and a non-metallic sample cell is essential for running these m
 easurements to ensure the RF field penetrates the sample. Initial measurem
 ents were carried out using an existing cell with a body made from PEEK po
 lymer\, using a 1/16” capillary to enable vapour to be introduced into t
 he cell in-situ. Unfortunately\, several significant problems were encount
 ered during initial experiments\, the most serious being a temporal instab
 ility in the signals measured for both pure silica and for systems loaded 
 with small pressures of benzene. This paper reports in detail on the probl
 ems encountered using the PEEK cell\, and then discusses the development o
 f a more reliable experimental setup giving better reproducibility for the
 se measurements. The new sample cell has been fabricated from Shapal\, a c
 eramic material with good thermal properties. Previous experience of using
  Shapal components in gas RF cells has suggested this is a ‘clean’ mat
 erial that gives none of the outgassing issues previously associated with 
 PEEK. While rebuilding the cell\, the opportunity was also taken to improv
 e the conductance of the vapour transfer tube. The success of the new cell
  is demonstrated both through off-line tests and by muon measurements\, in
 cluding a series of TF 2G muonium spin precession measurements designed to
  verify the temporal stability of the experimental setup. Finally\, an RF 
 cavity was fashioned\, and RF measurements made for muons stopped in bare 
 silica\, with signals from both diamagnetic and paramagnetic muon states c
 learly seen.\n\nhttps://indico.stfc.ac.uk/event/53/contributions/3786/
LOCATION:Science and Technology Campus\, University of Parma
URL:https://indico.stfc.ac.uk/event/53/contributions/3786/
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