Preparing replica film of specimen for electron microscopy

• US 4,447,374 A
• Filed: 03/10/1982
• Issued: 05/08/1984
• Est. Priority Date: 12/05/1979
• Status: Expired due to Term

• Current Assignee: Tokyo Metropolitan Institute of Medical Science
• Original Assignee: Tokyo Metropolitan Institute of Medical Science
• Inventors: Tanaka, Akira
• Primary Examiner(s): THURLOW, JEFFERY
• Application Number:
  US06/356,734
• Time in Patent Office: 790 Days
• Field of Search: 264/22, 264/81, 264/83, 264/220-221, 264/2.5, 264/28, 427/4, 427/39, 427/41, 250/311, 250/326, 250/441.1, 250/442.1, 204/165, 428/15-17
• US Class Current: 264/483
• CPC Class Codes: G01N 1/2806 Means for preparing replicas of specimens, e.g. for microscopal analysis
• CPC Class Codes: H01J 37/32 Gas-filled discharge tubes heating by discharge H05B

Abstract

A uniform thin replica film of a specimen for electron microscopy having a high resolution power such as approximately 1 Å is presented. This uniform thin replica film is directly prepared on the specimen by a plasma polymerization technique by depositing organic monomer vapors on a specimen placed on a negative electrode in a high vacuum atmosphere. The deposition is carried out by applying a discharge voltage of from 0.5 to 3 K.V.D.C. between a pair of positive and negative electrodes for 1 to 15 minutes to effect a glow discharge under the conditions of a current density of the glow discharge of from 0.1 and 2 mA/cm² and a gas pressure of from 1 to 10^-2 Torr in the system.

Claims

1. A method for preparing a replica of a specimen suitable for use in transmission-type electron microscopy and which is in the form of a film comprising the steps of:

(a) providing an apparatus comprising a pair of electrodes, one being an upper positive electrode and the other being a lower negative electrode which parallelly face each other with a distance therebetween and which are arranged in a vacuum vessel on a base plate, said pair of electrodes being electrically and thermically insulated from the vacuum vessel and the base plate and being surrounded by minute discharge prevention cylinders;

(b) placing the specimen on the surface of the negative electrode;

(c) evacuating the atmosphere within the apparatus with a vacuum pump so as to produce a high vacuum of approximately from 10^-5 to 10^-6 Torr within the apparatus;

(d) introducing organic monomer vapors or a mixture thereof with a small amount of an inert or active gas into the apparatus to produce a gas pressure of approximately from 1 to 10^-2 Torr in the apparatus;

(e) applying a direct discharge voltage of from 0.5 to 3 KV between said two electrodes for 1 to 15 minutes to effect a glow discharge, while the current density of the glow discharge is maintained between 0.1 and 2 mA/cm² by adjusting the flow rate of the organic monomer vapors to the apparatus and the flow rate of the evacuation gas from the apparatus, whereby a polymer substance film having a uniform thickness is formed on the surface of the specimen by the diffusion effect of plasma molecules;

(f) removing the specimen having the polymer substance film thereon from the apparatus after putting the pressure of the atmosphere within the apparatus back to an ordinary pressure; and

(g) dissolving the specimen in a solvent which does not dissolve the polymer substance film, but dissolves the specimen, to thereby separate the polymer substance film from the specimen.

2. A method as claimed in claim 1, wherein said organic monomer is at least one compound selected from the group consisting of ethylene, propylene, benzene, toluene, xylene, styrene, chlorobenzene, 1, 2, 4-trichlorobenzene, ferrocene, ethylbenzene, ethylene chloride, propylene oxide, methyl methacrylate, n-butyl methacrylate, 1,2-epoxy butane and 1,2-epoxy ethylbenzene.