Add new components to HeNDI (descriptions here!)

[hcientist]

Using the documentation here: https://github.com/RastonLab/Virtual-HeNDI-Spectrometer/issues/2

NEEDS TO BE BROKEN DOWN MORE

• Drawing of actual components?
• Hover text?
• Interior views?
• (possibly more)

Add new components

• Ion Gauge (3)
• Diffusion Pump (2)
• Turbo Pump
• Rotary Pump
• Salt Window
• Laser Symbol

[hcientist]

@spectroscopy please let us know what text should appear when hovering on the new components

[spectroscopy]

Note: Numbering of like components is from left to right

Ion Gauge (1): Pressure of the Detection Chamber, which is similar to that maintained at CERN (close to the vacuum found on the Moons surface).

Ion Gauge (2): Pressure of the Doping Chamber.

Ion Gauge (3): Pressure of the Source Chamber. It is relatively high due to the large amount of helium that flows through the nozzle.

Diffusion Pump (1): Evacuates the Doping Chamber by means of oil vapor convection currents.

Diffusion Pump (2): Evacuates the Source Chamber by means of oil vapor convection currents.

Turbomolecular Pump: Evacuates the Detection Chamber by means of an axial compressor which consists of a stack of fans that 'push" molecules to the exhaust. The fans rotate at a frequency of ~1 kHz.

Rotary Pump: Backs the turbo and diffusion pumps, which require a foreline pressure of <100 mTorr. The exhaust gas is directed to the rooftop.

Salt Window: This is a thin window (1-5 mm) that is transperant to infrared radiation. Typical materials are BaF₂, CaF₂, and ZnSe.

Laser Symbol: The output from a narrow linewidth quantum cascade laser is overlapped with the helium nanodroplet beam. Before entering the vacuum chamber through the salt window, a small fraction of radiation is reflected to a power meter ("P") and wavemeter ("λ"); the mechanical chopper wheel modulates the laser beam at a frequency of ~100 Hz, which serves as the reference for the lock-in amplifier.

Needle Valve: Used for precise control of the flow of analyte molecules into the doping chamber.

[spectroscopy]

Changes to existing text:

Detection Chamber: Houses a mass spectrometer which is used to detect helium nanodroplets.

Source Chamber: This is where helium nanodroplets are formed.

Quadrupole Mass Spectrometer: This instrument ionizes helium nanodroplets, and deflects the charged fragments through a quadrupole mass analyzer (mass filter), and unto an electron multiplier tube. The output is processed with a lock-in amplifier that is referenced to the frequency of the chopper wheel. The resulting signal is proportional to N²ᐟ³, where N is the average number of helium atoms per droplet.

Infrared Laser Beam: This overlaps with the helium nanodroplet beam. When resonant with a rovibrational transition of an analyte (e.g., R(0) of OCS), it can absorb a photon. This is followed by rapid relaxation, whereby the analyte transfers the rovibrational energy to the surrounding droplet, which results in the evaporation of helium (1 atom for every 5 cm⁻¹). This causes a decrease in the signal from the mass spectrometer. A "depletion" spectrum is generated by plotting the inverted signal against the wavenumber of the laser.

Coldhead: This is a large copper rod which is cooled to ~10 K by a closed-cycle cryostat.

Nozzle: The high pressure (>10 atm) helium gas which is precooled from thermal contact with the coldhead, is ejected from the nozzle into the vacuum chamber, where collisional cooling and condensation occurs. The resulting helium nanodroplets have an average size in excess of 1000 atoms, and a temperature of ~0.4 K, which renders them almost entirely superfluid.