Expand your potential...

 

• Determine effective dipole moments through simple surface potential measurements of a compressed film.

 

• Combine surface potential and surface pressure data to determine the molecular orientation.

 

• Confirm that changes are made to the electronic structure of molecules with even the smallest of structure modifications.

 

• Quantify the effects of changes to molecular structure through positional offsets and peak values of the surface potential plots.

 

• Observe and follow complex formations between monolayers, subphase species or adsorbates.

 

• Explore the fascinating world of the floating gaseous phase.

 

Principle of operation

The Nima Surface Potential Sensor is an instrument that offers complementary data on the packing and orientations of surfactant molecules within the sampling region of the Langmuir film. Whereas the surface pressure is measured as a change in the surface tension of the air-water interface, the Surface Potential Sensor measures the potential difference above and below the film and is sensitive to the sum of all the individual dipole moments.

Changes in surface pressure are only detected once a closely packed monolayer begins to form. Changes in the surface potential, however, can be measured as soon as molecules with dipoles appear at the surface. As the orientation of the molecules change during compression, the alignments of the dipoles cause a large change in the surface potential. This is clearly demonstrated in the plot shown above in the image previwer. The example shows the fascinating relationship between surface pressure and surface potential for DPPC, a commonly studied phospolipid molecule.

 

Setting up

The Nima Surface Potential Sensor is intended for use with a Langmuir or LB Deposition Trough. The instrument is supplied with an adjustable stand to position it over any size of trough. A counter-electrode plate is connected to the instrument and placed into the subphase within the trough. All troughs that can accommodate the counter-electrode plate, dimensions 50x35x2mm, can be used with the Nima Surface Potential Sensor.

The Nima Surface Potential Sensor connects directly to your existing Nima Interface Unit, supplied with all Nima Langmuir and LB Deposition Troughs. IU4 Computer Interface Units are available if you wish to operate this instrument as a stand-alone device without a Langmuir or LB Deposition Trough.

The instrument will be calibrated during the product testing stage, before being shipped. If a recalibration is required, this can be performed using the supplied calibration device.

 

Software

The Nima Surface Potential Sensor does not require any additional software. The latest version of Nima trough software will display recordings of both surface pressure and surface potential on the same plot. Colour coded axes and plots ensure that the two recordings are clearly presented.

 

Specifications

Input range: -2.5V to +2.5V

Accuracy: +/- 1mV

Response time: Proportional to distance but less than 1s when positioned 1mm above monolayer

Calibration settings: Electric field measured at 2mm separation using 0V and 1.5V (calibration kit supplied)

Stand base height: 19mm

Maximum height of sensor on adjustable stand: 158mm

Counter-electrode plate dimensions: 35x50x2mm, vertical electrode arm length 20mm

Software: fully incorporated into Nima trough control software

 

We have price lists available for UK, Europe and USA. If you require a price list in your local currency or require a firm quotation please contact us.

All Nima instruments are covered by a three year warranty. If a fault develops during this time, we will repair the instrument free of charge.