title: SAXS anti-peaks reveal the length-scales of dual positive-negative and polar-apolar ordering in room-temperature ionic liquids.
abstract: Structural patterns that have the same spatial periodicity but a phase offset give rise to peaks and anti-peaks (negative-going peaks) at the same q value in the SAXS structure function S(q). As an example, in ionic liquids we often find charge alternation, and at the distance where one finds a density enhancement of charges of the same type one also finds a depletion of charges of opposite sign. Another such situation arises with polar-apolar densities. At distances where there is enhancement of same-type (polar-polar or apolar-apolar) densities there is also a depletion of opposite-type (polar-apolar) density. This gives rise to prepeaks and what we call same spatial periodicity anti-prepeaks.
authors.affiliation: Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Hemant K
authors.initials: HK
authors.lastname: Kashyap
authors.forename: Jeevapani J
authors.initials: JJ
authors.lastname: Hettige
authors.forename: Harsha V R
authors.initials: HV
authors.lastname: Annapureddy
authors.forename: Claudio J
authors.initials: CJ
authors.lastname: Margulis