Long life electron multiplier

A method of analyzing a sample, the method comprising:

• ionizing the sample with an ion source to produce ions;
• separating the ions based on mass-to-charge ratio in a mass analyzer;
• directing the ions to a conversion dynode to produce electrons;
• passing the electrons through an electron-transparent, gas-impermeable barrier of a housing of an electron multiplier to strike a first discrete electron emissive surface of a series of discrete electron emissive surfaces or a continuous electron emissive semiconductor surface;
• amplifying the electrons with the series of discrete electron emissive surfaces or the continuous electron emissive semiconductor surface;
• and
• producing a signal at an anode proportional to the amplified electrons reaching the anode, the signal being proportional to an amount of a compound in the sample.