Method and Apparatus for Improving Ion Transmission into a Mass Spectrometer

A system for mass spectra analysis of ions, the system comprising:

• an electrospray ion source for spraying a divergent beam of ions produced by charging droplets of a solution of molecules introduced into the electrospray source, the electrospray ion source comprising an exit port from which the ions are electrosprayed at atmosphere;
• a mass analyzer having an inlet port enclosed in a vacuum housing for receiving the ions formed in the electrospray ion source to be analyzed;
• and
• an ion transmission interface for transferring the ions from the electrospray ion source to the vacuum housing, the ion transmission interface comprising:
• a diverging duct electrode comprising a tube having a continuous inner surface defining an entrance aperture and an exit aperture and an enclosed diverging channel therebetween, the exit aperture having an inner diameter larger than an inner diameter of the entrance aperture, the entrance aperture positioned proximate the exit port of the electrospray ion source and receiving the ions at atmosphere from the electrospray ion source, the diverging channel narrowing the beam of ions;
• and
• an electrode holder coupled between the exit aperture of the diverging duct electrode and the vacuum housing for transporting the ions to the mass analyzer under vacuum.