A new visual illusion is presented. When two neon-coloured illusory bands overlap each other, the filling-in at the region of overlap is perceived as different from those of the overlapping bands, resulting in an additional illusory shape at the region of overlap. An experiment with ten na|« ve participants was performed to measure the illusory percept. The results show that illusory surfaces m...

We report absorption spectra for Ag(7), Ag(9), and Ag(11) in an argon matrix grown at a temperature of 28 K and compare them with previous spectra of the same species measured in matrices of argon grown at lower temperatures as well as in neon matrices. We discuss the discrepancies in the light of the matrix crystallinity and show that this leads to an understanding of the influence of the matr...

If a pattern of concentric circles, interrupted so as to produce the perception of a subjective bar extending from the centre to the periphery of the pattern, was slowly rotated in a plane perpendicular to the line of sight, observers reported seeing the bar slanted in depth and moving over complete and stationary concentric circles. When the interrupted concentric circles were completed by red...

An experimental and theoretical study of ground-state photoionization of neon is presented in the photon energy range between 44 and 53 eV. This portion of the spectrum is characterized by a singly excited Rydberg series 2s2pnp , and by overlapping doubly excited Rydberg series 2s2p3snp and 2s2p3pnl (l5s ,d). With the use of synchrotron radiation of >3 meV spectral resolution, numerous hitherto...

Despite its apparent simplicity and extensive theoretical investigations, the issue of what is the shape of the helium trimer is still debated in the literature. After reviewing previous conflicting interpretations of computational studies, we introduce the angle-angle distribution function as a tool to discuss in a simple way the shape of any trimer. We compute this function along with many di...

We discuss the possibility to detect O/Ne white dwarfs by evidence for Ne overabundances. The hottest known WD, H1504+65, could be the only single WD for which we might be able to proof its O/Ne nature directly. Apart from this, strong Ne abundances are known or suspected only from binary systems, namely from a few novae, and from a handful of LMXBs. We try to verify the hypothesis that the lat...