Mass marking for spectrometry using programmed molecule clusters

Claim 2

In mass spectrometry, a method of marking molecular weights at regular mass intervals over a mass range within which ions of a gas to be analyzed are expected in order to provide a reference for identification of said ions, said method comprising the steps of: a. selecting a marker gas having molecules of known molecular weight and characterized by the capability of forming molecule clusters at said regular mass intervals in a controlled expansion; b. expanding said marker gas through a nozzle into a region of reduced pressure; c. controlling the conditions under which said expansion is effected to cause partial condensation of the marker gas and attendant formation of a beam of molecule clusters having molecular weights distributed at said intervals in said mass range; d. ionizing the molecule clusters of said beam; and e. detecting the molecular weights of the ionized clusters and the molecular weights of the ions of the gas to be analyzed to thereby provide reference markings from which the ions may be identified.

Claim 3

The method as claimed in claim 1, wherein said step (c) includes preselecting the source pressure of said marker gas, the temperature thereof, and the configuration of said nozzle to effect said partial condensation and attendant cluster formation.

Claim 4

The method as claimed in claim 1, wherein said step (c) includes preselecting the source pressure of said marker gas, the temperature thereof, and the configuration of said nozzle to cause the intensity of the molecule clusters to be relatively uniform throughout said mass range.

Claim 5

The method as claimed in claim 1, wherein said step (c) includes varying the source pressure of said marker gas during detection of the molecular weights of the ionized clusters to optimize the intensity of the molecule clusters over said mass range.

Claim 6

The method as claimed in claim 1, wherein said detection of the molecular weights of the ionized clusters in said step (e) includes scanning said mass range in a mass spectrometer, and wherein said step (c) includes varying the source pressure of said marker gas during said scanning to optimize the intensity of the molecule clusters over said mass range.

Claim 7

The method as claimed in claim 1, wherein said step (b) includes intermittently delivering said marker gas to said nozzle to reduce the amount thereof subjected to expansion.

Claim 8

The method as claimed in claim 1, wherein is provided the additional step of modulating said beam of molecule clusters prior to detecting the molecular weights thereof in said step (e), whereby to impart a characteristic signature to the ionized clusters.

Claim 9

The method as claimed in claim 1, wherein said marker gas includes one of the rare gases selected from the group consisting of neon, argon, krypton and xenon.

Claim 10

In combination with a mass spectrometer having an ion source for receiving and ionizing a gas to be analyzed, mass marker apparatus including: means for supplying a marker gas under pressure having molecules of known molecular weight and characterized by the capability of forming molecule clusters at regular mass intervals over a preselected mass range in a controlled expansion of said marker gas; a nozzle communicating with said supplying means for causing expansion of said marker gas as it passes therethrough into a region of reduced pressure; conduit structure having said nozzle disposed therein and presenting said region at the nozzle; and means communicating with said structure for maintaining said region in an evacuated condition, the pressure of said marker gas and the configuration of said nozzle being selected to cause partial condensation of the marker gas discharging from the nozzle and attendant formation of a beam of molecule clusters having molecular weights distributed at said intervals in said mass range, said structure having outlet means communicating with said ion source to direct said beam into said source for ionization of the molecule clusters, whereby to provide the spectrometer readout with reference markings for identification of the ions of the gas to be analyzed.

Claim 11

In combination with a mass spectrometer having an ion source for receiving and ionizing a gas to be analyzed, mass marker apparatus including: means for supplying a marker gas under pressure having molecules of known molecular weight and characterized by the capability of forming molecule clusters at regular mass intervals over a preselected mass range in a controlled expansion of said marker gas; a nozzle communicating with said supplying means for causing expansion of said marker gas as it passes therethrough into a region of reduced pressure; conduit structure having said nozzle disposed therein and presenting said region at the nozzle; and means communicating with said structure for maintaining said region in an evacuated condition, the pressure of said marker gas and the configuration of said nozzle being selected to cause partial condensation of the marker gas discharging from the nozzle and attendant formation of a beam of molecule clusters having molecular weights distributed at said intervals in said mass range, said structure having outlet means communicating with said ion source to direct said beam into said source for ionization of the molecule clusters, whereby to provide the spectrometer readout with reference markings for identification of the ions of the gas to be analyzed.

Claim 12

In the combination as claimed in claim 9, wherein said spectrometer scans said mass range in the detection of the molecular weights of ions emanating from said ion source, and wherein said apparatus further includes means coupled with said supplying means and responsive to the progress of the scan of said mass range for varying the supply pressure of said marker gas to optimize the intensity of the molecule clusters over said mass range.

Claim 13

The apparatus as claimed in claim 9, wherein an electrically responsive valve is provided in association with said nozzle for controlling the discharge of said marker gas therefrom, and means coupled with said valve for exciting the latter with time-spaced electrical pulses to cause intermittent operation of the valve and attendant reduction of the amount of said marker gas discharged from the nozzle, thereby minimizing the gas load.

Claim 14

The apparatus as claimed in claim 9, wherein chopper means is provided in the path of said beam for modulating the latter, whereby to impart a characteristic signature to the molecule clusters.

Claim 15

The apparatus as claimed in claim 9, wherein said nozzle and said structure are arranged to direct said beam into said ion source along a rectilinear path.