ESR Investigations of Spin‐Pair Radicals in Nitrogen‐Helium Solids Conference Paper uri icon


  • We have investigated nitrogen-helium solids by X-band CW-ESR. Our samples, containing molecules and atoms of either the 14N or the 15N isotope, were produced from N2:He gas mixtures with different nitrogen impurity concentrations ranging from 0.25% to 1%. Samples were formed in a helium cryostat at 1.5 K by applying a radio-frequency discharge to a gas mixture jet that was then introduced into superfluid 4He. We achieved average concentrations of stabilized nitrogen atoms as high as 21019 atoms/cm3. We observed a strong ESR signal of stabilized nitrogen atoms at ∼3235 Oe. For the first time we also detected weak ESR signals corresponding to the ΔMS = 2 transitions of 14N14N or 15N15N spin-pair radicals in nitrogen-helium solids at ∼1617 Oe. The intensities of these signals were ∼1000 or more times smaller than those of the main atomic signals. We investigated the thermal stability of the nitrogen-helium solids and observed the spin-pair radical signals in dry samples at T = 3.1 K. After explosive disintegration of the samples at ∼3.3 K, the spin-pair radical signal disappeared. © 2006 American Institute of Physics.

author list (cited authors)

  • Vehmanen, E., Khmelenko, V. V., Bernard, E. P., Kunttu, H., & Lee, D. M.

publication date

  • January 1, 2006 11:11 AM


  • AIP  Publisher