X-ray or gamma ray systems or devices – Specific application – Fluorescence
Reexamination Certificate
2000-04-11
2003-03-25
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Fluorescence
C378S044000
Reexamination Certificate
active
06539075
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fluorescent X-ray analyzing apparatus for conducting element analysis by detecting a secondarily-produced X-ray emanating from a sample in response to illuminating an X-ray onto the sample.
2. Description of the Prior Art
There are broad uses of the fluorescent X-ray analyzing apparatus for conducting element analysis by illuminating a primary X-ray onto a sample and detecting an X-ray secondarily produced from the sample in response thereto.
Particularly, there is a proposal of a method in which, in order to measure an element contained in slight amount contained in a solution, approximately 50 micro-liters of a solution is dripped onto an extremely-thin organic thin film through a micropipette and then dried so that the “residue” on the organic thin film can be thereafter measured by a fluorescent X-ray analyzing apparatus (called an organic thin film drip and dry method) (disclosed in 34th X-ray analysis forum, on Nov. 10, 1998). The principle of this measurement is briefly explained.
Referring to
FIG. 2
, there is illustrated a schematic view where measurement is conducted with a conventionally-used fluorescent X-ray analyzing apparatus.
Numeral
1
is a sample stage and numeral
3
is an organic thin film support member.
Further, numeral
4
is a residue and numeral
5
is an organic thin film.
Furthermore, numeral
10
is a X-ray source and numeral
11
is a detector.
When illuminating a primary x-ray to a sample, an X-ray spectrum obtained by a detector includes (1) a fluorescent X-ray due to an element contained in the sample and (2) a component of the primary X-ray reaching the detector due to scattering of the primary X-ray (includes diffraction) upon the sample. The scattering X-ray might form a broad background over a wide energy range of the spectrum. In the meanwhile, because the scattering X-ray decreases in intensity with a decrease in sample thickness, it is possible to obtain a spectrum with a low background.
The relationship between a detection lower limit and a background intensity can be defined as follows:
(X-ray intensity obtained from element concentration at detection lower limit)=3× (background X-ray intensity).
Accordingly, the use of the organic thin film dip-and-dry method greatly improves a lower limit of detection as compared to the method of analysis that directly illuminates an X-ray to a solution sample.
In the meanwhile, in the fluorescent X-ray analyzing apparatus for measuring an organic thin film formed through dripping and drying a sample, a top-radiation system for illuminating a primary X-ray from the sample above is adopted so as not to spill a residue out of the organic thin film. Meanwhile, a fluorescent X-ray analysis apparatus is used to illuminate a primary X-ray only to an area of the residue. This apparatus is provided with a collimator for forming a beam as fine as about 1 to 2 mm, a sample stage for positioning a the residue, and a sample observation mechanism.
In the conventional apparatus, however, the sample stage is made of a resin or aluminum. Accordingly, when a primary X-ray is illuminated on to an organic thin film, the X-ray transmitting through the organic thin film impinges upon the sample stage. This results in a problem that the detector detect a scattering X-ray from the stage and a fluorescent X-ray thus causing a background.
SUMMARY OF THE INVENTION
In order to solve the problem, in the present invention, a hole is formed in a sample stage which has a greater diameter than that of a beam of a primary X-ray and a coating film is formed of a heavy metal on the bottom and inner surfaces of the hole. The sample stage is made lightweight to have a movement mechanism, and uses resin or light metal such as aluminum. Because the intensity of a scattering X-ray is inversely proportional to a mean atomic number of an object, the scattering X-ray from the sample stage formed of resin or light metal is extremely high in intensity. To form the entire sample stage of a heavy metal is not advantageous because of a resulting increase in weight. Accordingly, the sample stage itself is formed of a resin or a lightweight material, and a hole is formed in a position so that a primary X-ray is caused to pass therethrough. The hole at its bottom surface where the primary X-ray is to be finally stopped is made of a heavy metal. Due to this, the scattering X-ray is reduced in intensity without requiring weight increase for the entire stage. Furthermore, a heavy metal coating film is also formed on an inner surface of the hole, thereby preventing scattering at the inner surface. Meanwhile, the scattering X-ray from the heavy metal coating film, although low in intensity, possibly cause an interference peak on a spectrum. However, in the case that the coating film is formed of the same substance as an element of a target material of the X-ray tube, an effect is obtained in that the interference peak will not increase because of the fact that a characteristic X-ray peak concerning the target material element exists in nature on the spectrum.
REFERENCES:
patent: 4974244 (1990-11-01), Torrisi et al.
patent: 403225267 (1991-10-01), None
Adams & Wilks
Kim Robert H.
Seiko Instruments Inc.
Song Hoon K.
LandOfFree
Slight amount sample analyzing apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Slight amount sample analyzing apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Slight amount sample analyzing apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3020512