Cluster ions DN+ ejected from dense and ultra-dense deuterium by Coulomb explosions: Fragment rotation and D+ backscattering from ultra-dense clusters in the surface phase

The two forms of condensed atomic deuterium, dense deuterium D(1) and ultra-dense deuterium D(−1), can be studied by laser-induced Coulomb explosion time-of-flight mass spectrometry and neutral time-of-flight. In the present study pulsed laser intensity below 1014 W cm−2 is used. Cluster ions DN+ from D(1) are observed with N = 3, 4, 12 and 17, thus not in close-packed forms. Clusters DN(1) are mainly in the form of chains of D2 and D3 groups, a shape derived from the D(−1) material which D(1) is spontaneously converted to. Only atomic ions D+ with initial kinetic energy of hundreds of eV are observed from D(−1). Half of these ions are ejected from the emitter surface, half of them penetrate into the ultra-dense D(−1) layer on the emitter surface. This second half of the ions is reflected completely from the surface layer formed by ultra-dense D(−1) strongly bonded clusters D3(−1) and D4(−1).

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► Cluster ions DN+ from D(1) are observed with N = 3, 4, 12 and 17, not in close-packed forms.
► Clusters DN(1) from D(1) are mainly in the form of chains of D2 and D3 groups.
► Only atomic ions D+ with initial kinetic energy of hundreds of eV are observed from D(−1).
► Half of the D+ ions are ejected from the emitter surface, half of them penetrate into the ultra-dense D(−1) layer on the emitter surface. This second half of the ions is reflected completely from the surface layer formed by clusters D3(−1) and D4(−1).