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"Split Exposure" for Determining Optical Emissions on a Spectograph

IP.com Disclosure Number: IPCOM000082624D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Zmudzinski, JV: AUTHOR

Abstract

An optical emission spectograph, equipped with automatic plate racking and a rotating sector, is normally used to determine elements within an unknown sample. However, it is difficult to obtain maximum plate intensity and sensitivity of volatile spectra elements such as sodium, arsenic and zinc on one plate.

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"Split Exposure" for Determining Optical Emissions on a Spectograph

An optical emission spectograph, equipped with automatic plate racking and a rotating sector, is normally used to determine elements within an unknown sample. However, it is difficult to obtain maximum plate intensity and sensitivity of volatile spectra elements such as sodium, arsenic and zinc on one plate.

The "split exposure" method increases, in some cases as much as ten fold, the intensity and sensitivity of elements on a plate and increases the sample's matrix flexibility.

The total spectra height on one plate is 3mm. The sector exposes a first portion of the plate at a predetermined light intensity while the sample arcs. The plate is then racked so that another portion of the plate, which partially overlaps the first portion is exposed at a different light intensity until the sample burns to completion.

For example, during the first ten seconds of arcing with 100% transmittance, sodium burns off quickly and is recorded on the lower and middle portions of 3mm of the plate (Fig. 1). Setting the sector an additional ten seconds at 50% transmittal the middle and upper portions of the same plate is recorded with the middle portion overlapping the first exposure (Fig. 2). The resultant spectra is shown in Fig. 3.

The spectra varies depending on the element's volatility. Figs. 1-3 and Figs. 4-6 show the results for a nonvolatile and volatile element, respectively.

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