title: Irregular Liesegang-type patterns in gas phase revisited. I. Experimental setup, data processing, and test of the spacing law.
abstract: Since the early work on Liesegang rings in gels, they have been a reference point for the study of pattern formation in chemical physics. Here we present a variant of the Liesegang experiment in gas phase, where ammonia and hydrochloric acid react within a glass tube producing a precipitate, which deposits along the tube wall producing a spatial pattern. With this apparently simple experiment a wide range of rich phenomenon can be observed due to the presence of convective flows and irregular dynamics reminiscent of turbulent behavior, for which precise measurements are scarce. In this first part of our work, we describe in detail the experimental setup, the method of data acquisition, the image processing, and the procedure used to obtain an intensity profile, which is representative of the amount of precipitate deposited at the tube walls. Special attention is devoted to the techniques rendering a data series reliable for statistical studies and model building, which may contribute to a characterization and understanding of the pattern formation phenomenon under consideration. As a first step in this direction, based on our data, we are able to show that the observed band pattern follows, with slight deviations, the spacing law encountered in common Liesegang rings, despite that the experimental conditions are very different. A further statistical correlation analysis of the data constitutes Paper II of this research.
authors.affiliation: Centro de Investigación en Ciencias, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico.
authors.forename: José C
authors.initials: JC
authors.lastname: Torres-Guzmán
authors.affiliation: Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico.
authors.forename: Thomas
authors.initials: T
authors.lastname: Buhse
authors.affiliation: Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, Cuernavaca, Morelos 62251, Mexico.
authors.forename: Elsa María
authors.initials: EM
authors.lastname: de la Calleja
authors.affiliation: Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, Cuernavaca, Morelos 62251, Mexico.
authors.forename: Alfredo
authors.initials: A
authors.lastname: González-Espinoza
authors.affiliation: Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, Cuernavaca, Morelos 62251, Mexico.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Martínez-Mekler
authors.affiliation: Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico.
authors.forename: Fernando
authors.initials: F
authors.lastname: Montoya-Nava
authors.affiliation: Centro de Investigación en Ciencias, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico.
authors.forename: Elizeth
authors.initials: E
authors.lastname: Ramírez-Álvarez
authors.affiliation: Centro de Investigación en Ciencias, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico.
authors.forename: Marco
authors.initials: M
authors.lastname: Rivera-Islas
authors.affiliation: Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico.
authors.forename: Aurora
authors.initials: A
authors.lastname: Rodríguez-Álvarez
authors.affiliation: Centro de Investigación en Ciencias, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico.
authors.forename: Markus F
authors.initials: MF
authors.lastname: Müller