Atomic trap trace analysis

{{Short description|Trace analysis method}}

Atom Trap Trace Analysis (ATTA) is an extremely sensitive trace analysis method developed by Argonne National Lab (ANL). ATTA is used on long-lived, stable radioisotopes such as {{math|⁸¹Kr}}, {{math|⁸⁵Kr}}, and {{math|³⁹Ar}}. By using a laser that is locked to an atomic transition, a CCD or PMT will detect the laser induced fluorescence to allow highly selective, parts-per-trillion to parts-per-quadrillion concentration measurement with single atom detection.{{cite journal

| author= Chen, C. Y.

| author2=Li, Y. M.

| author3=Bailey, K.

| author4=O'Connor, T.P..

| author5=Young, L.

| author6=Lu. Z.T.

| title= Ultrasensitive isotope trace analyses with a magneto-optical trap.

| year=1999

| journal=Science

| volume=286

| issue=5442

| pages=1139–1141

| doi= 10.1126/science.286.5442.1139| pmid=10550048

| citeseerx=10.1.1.515.3362

}} This method is useful for atomic transport processes, such as in the atmosphere, geological dating, as well as noble gas purification.{{cite journal

| author= Aprile, E.

| author2=Yoon, T.

| author3=Loose, A.

| author4=Goetzke, L.W.

| author5=Zelevinsky, T.

| title= An atom trap trace analysis system for measuring krypton contamination in xenon dark matter detectors.

| year=2013

| journal=Review of Scientific Instruments

| volume=84

| issue=9

| pages=093105–093105–6

| doi= 10.1063/1.4821879

| pmid=24089814

|bibcode = 2013RScI...84i3105A| arxiv=1305.6510

| s2cid=7228426

}}

ATTA measurements are possible only if the atoms are excited to a metastable state prior to detection. The main difficulty to accomplishing this is the large energy gap (10-20 eV) between the ground and excited state. The current solution is to use an RF discharge, which is a brute force technique that is inefficient and leads to complications such contamination of the walls from ion sputtering and high gas density. A new scheme for generating a metastable beam which can achieve a cleaner, slower, and preferably more intense source would provide a substantial advance to ATTA technology. All-optical techniques have been considered, but have not yet been able to compete with the discharge source.{{cite journal

| author=Kohler, M.

| author2=Daerr, H.

| author3=Sahling, P.

| author4=Sieveke, C.

| author5=Jerschabek, N.

| author6=Kalinowski, M.B.

| author7=Becker, C.

| author8=Sengstock, K.

| title= All-optical production and trapping of metastable noble-gas atoms down to the single-atom regime.

| year=2014

| journal=Europhysics Letters

| volume=108

| issue=1

| pages=13001

| doi= 10.1209/0295-5075/108/13001

| bibcode=2014EL....10813001K

| arxiv=1408.1794

| s2cid=32215343

}} A new technique for generation of metastable krypton involves the use of a two photon transition driven by a pulsed, far-UV laser to populate the excited state which decays to the metastable state with high probability.{{cite journal

| author=Dakka, M.A.

| author2=Tsiminis, G.

| author3=Glover, R.D.

| author4=Perrella, C.

| author5=Moffatt, J.

| author6=Spooner, N.A.

| author7=Moffatt, R.T.

| author8=Light, P.S.

| author9=Luiten, A.N.

| title= Laser-based metastable krypton generation.

| year=2018

| journal=Physical Review Letters

| volume=121

| issue=9

| pages=093201

| doi= 10.1103/PhysRevLett.121.093201

| pmid=30230900

| bibcode=2018PhRvL.121i3201D

| arxiv=1805.05669

| s2cid=51687605

}}