US 2920201 A
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M. R. ANNIS ErAl. 2,920,201
APPARATUS FOR EXCITING ATOMS IN FLUIDS Filed Nov. 18, 1957 Jan. 5, 19601 METHOD AND INVENTOR. MAX R. A'NNIS, FRED A. BROOKS JR.
4M4 xTaM ATTORNEY.
United States Patent METHOD AND APPARATUS FOR EXCITING ATOMS IN FLUIDS .Max R. Annis, Baytown, and Fred A. Brooks, In, Houston,,Tex., assignors, by mesne assignments, to Jersey Production ResearchCompany, Tulsa, Okla., a corporation of Delaware Application November 18, 1957, Serial No. 696,979 5 Claims. (Cl. 250-495 sparking method.
Atoms can be raised from their normal state to higher energy states by bombarding them with electrons, or by subjecting them to high temperatures in a flame 'or an electric arc, or by allowing them to absorbradiant energy from an external source. A higher than normal energy state is generally referred to as an excited state; When the atoms return to a state of lower energy, radiation is emitted in the form of photons of very definite frequency.
The emission spectrograph is commonly used for the analysis of chemical elements and occasionally for the analysis of certain chemical compounds. The sample atoms and molecules are first excited. Upon returning to normal they emit the characteristic radiations in the form of light rays. These light rays are passed through a lens system, a collumation system, a ditfraction grating, and then usually displayed on a photographic plate. The light rays are recorded on the photographic plate as vertical lines at a position determined by the frequency of the light. The frequency of any line of the emission spectrum is proportional to the difference between the values of the energies of two states of the atom or molecule emitting the radiation; that is,
Where 1 is the frequency of the light, E is the initial energy of the atom or molecule; E is the final energy of the molecular or atom, and h is the Planck constant.
The invention described herein is a new method and apparatus for exciting atoms of a fluid by arcing method. In using the arcing method, a voltage isdeveloped across a pair of electrodes having suflicient energy to excite the atoms of a fluid to be investigated.
A disadvantage of current methods of exciting atoms of a sample by the means of the arcing method is that unwanted background appears and contaminates the photographic plate, thereby interfering'with the detection of the desired light rays. This unwanted background arises from the interaction of the material the electrodes are made of with elements of the air contained in the arc. For example, with carbon electrodes, the carbon of the electrodes and the nitrogen atoms of the air are violently thrown together and frequently combine. In the process of combining and disassociating, the CN molecules give ofi a very large number of bands of light rays that are poorly resolved which give rise to an unwanted background. The unwanted background produced thereby is commonly referred to as the cyanogen bands. These bands may range from 3590 to 3583, 3883 to 3850, and 42l6'to 4152 angstroms. In actual operation, this background appears as a universal darkening throughout much of the wave length region of interest on the photographic plates.
is contained in the chamber 14. This fluid may suitably In attempting to detect the presence and darkness of an individual line representative of a specific chemical element, it is necessary to clearly distinguish this line from the unwanted background. The cyanogen band makes this diflicult and consequently prevents the detection of lines caused by small amounts of a given chemical element which produces very light emission lines. For example, the cyanogen band interferes with the detection of small amounts of rubidium. The emission line of rubidium appears at 4202 angstroms.
This invention is a new method and apparatus for excit-' ing atoms of a fluid sample which substantially eliminates; the production of unwanted background caused by the interaction of the material of the electrodes with elements contained in the air in the arcing region. For example, our new method and apparatus substantially eliminates the production of the cyanogen band when carbon electrodes are used. p
Briefly described, the method consists of providing a continuous supply of liquid to each electrode. The sample fluid may be supplied to both electrodes, or in the alternative, to one electrode with distilled water supplied to the other. A voltage is then applied across the electrodes of sufficient magnitude to excite the atoms in the fluid sample to higher energy states.
One type of apparatus which is used in carrying out the new method includes a means for placing fluid on both electrodes. Means are provided for producing a voltage across the electrodes (which have fluid thereon) suflicient to excite the atoms in the fluid sample to a higher energy state.
A better understanding of the invention, as well as its many advantages, may be had by reference to the detailed description to follow and the single figure which shows a schematic drawing of our new apparatus for carrying out our new method.
The figure shows a first electrode 10 which is supported by an electrode supporting member 12.
Electrode 10 may be substantially cylindrical in shape and has a fluid chamber 14 formed therein. Some fluid be the solution to be analyzed or may be distilled water.
The electrode 10 may be made of carbon, which is a preferred material. The use of carbon insures excitaton of all of the elements of the fluid sample. Also, the carbon is porous, thus permitting the fluid in chamber 14 v to difiuse through the porous tip 16 of the electrode 10.
A fluid container support 18 is positioned below the electrode support 12. A fluid sample container 20 is disposed on container support 18. A portion of the fluid to be analyzed is placed in the fluid container 20.
A rotatable disc electrode 22 is mounted in spaced relation below the cylindrical electrode 10. The rotatable disc electrode 22, which is preferably also made of carbon, is disposed so as to dip into the fluid in container 20 and carry some of the fluid into the region between electrodes 10 and 22.
Voltage of sufficient magnitude to excite all of the atoms of the fluid is applied across the electrodes 10 and 22 to produce an arc in the arcing region between said electrodes. This is shown schematically by an AC. voltage source 24 having one terminal thereof connected to electrode 10 through line 26, and the other terminal connected to electrode 22 through line 28.
By providing means for placing fluid on both ofthe electrodes 10 and 22, the fluid sample is excited without the production of the unwanted association and disassocia- .It is to be understood that various modifications may be made in the foregoing method and apparatus without departing from the scope of the appended claims.
1. An apparatus for use .in exciting the atoms of elements of a liquid sample comprising: a substantially cylindrical electrode having a chamber in which some liquid is contained, said electrode being porous to permit liquid flow toward an end thereof; a container for holding some of the sample liquid; a rotatable disc electrode mounted in spaced relation to the cylindrical electrode and disposed so as to dip into the sample liquid in said container and carry some of the sample liquid into the region between said two electrodes; and means for producing a voltage across the electrodes sufiicient to excite the atoms of the sample liquid in said region to a higher energy state.
2. An apparatus in accordance with claim 1 wherein said electrodes are made of carbon.
3. A method of exciting atoms of elements of a liquid sample by the arcing method using two spaced electrodes comprising the steps of: providing a continuous supply of liquid to one electrode and a continuous supply .of sample liquid to the second electrode; and applying a voltage across the electrodes suflicient to excite the atoms in the sample liquid to higher energy states.
4. A method of exciting atoms of elements of a liquid sample by the arcing method using two spaced electrodes comprising the steps of: providing a continuous supply of distilled water to one electrode and a continuous supply of sample liquid to the second electrode; and applying a voltage across the electrodes sufiicient to excite the atoms in the sample liquid to higher energy states.
5. A method of exciting atoms of elements of a liquid sample by the arcing method using two spaced electrodes comprising the steps of: providing a continuous supply of sample liquid to one electrode and a continuous supply of sample liquid to the second electrode; and applying a voltage across the electrodes sufiicient'to excite the atoms in the sample liquid to higher energy states.
References Cited in the file of this patent UNITED STATES PATENTS 2,344,719 Nusbaum et al. Mar. 21, 1944 2,643,574 Todd Ian. 30, 1953 2,753,479 Aughey et al July 3, 1956 OTHER REFERENCES Catalogue from United Carbon Products Co., Inc..
circa-.March .1955, R0. Box 269, Bay City, Michigan.