Date:
Mon, 08/01/202412:00-13:30
Location:
Levin building, Lecture Hall No. 8
Lecturer:
Prof. Yaakov Weiss (HUJI)
For the last 20 years, laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS)
allowed fast and easy measurement of many trace elements in microinclusion-bearing diamonds.
In an attempt to analyze trace element concentrations in gem-quality diamonds, barren of visible
microinclusions aggregates, an ‘off-line’ approach was developed. This technique opened the
way for radiogenic isotope analyses, still, only diamonds with high total trace element
abundances could be analyzed.
Following the off-line concept, I developed an ablation technique of diamonds-in-water using a
‘powerful laser’ to significantly improve the amount of ablated material. The first generation used
a Spectra-Physics GCR-150-30 Q-switched Nd:YAG laser that allowed a high but variable
diamond ablation rate (between 3 and 14 mg h -1 ). However as the stage speed and incremental
movement were controlled manually during operation, the ablation pit morphology and spatial
depth were irregular and varied between ablations. The second generation off-line ablation system
in the diamond processing lab at the Hebrew University is a custom-made setup equipped with a
Spectra-Physics Talon 532-20 Nd:YV04 laser. The system is fully automated with a working area
of 20 mm × 20 mm × 20 mm, resolution of 0.5 µm, repeatability <±2 µm and a maximum speed
of 5 mm s -1 . Based on multiple ablation runs the new system's average ablation rate is 0.6 ±0.2 mg
h -1 , and we have managed to ablate up to 30 mg of a diamond.
The combination of a powerful laser and ablation in water has two major advantages. First, the
amount of diamond that can be ablated using such a laser in a timely manner is several mg.
Second, because the ablated area is underwater, the trapping efficiency is very high and allows
efficient retrieval of the nanosized analyte particles. In addition, all the material trapped in the
microinclusions is ablated and digested by acids, so possible elemental and isotopic fractionation
induced by ablation are avoided. Using the system and analyzing the ablated material by state-of-
the-art mass spectrometers we now get accurate trace-element analyses and Sr, Nd and Pb
isotopic data on individual microinclusion-bearing diamonds.
allowed fast and easy measurement of many trace elements in microinclusion-bearing diamonds.
In an attempt to analyze trace element concentrations in gem-quality diamonds, barren of visible
microinclusions aggregates, an ‘off-line’ approach was developed. This technique opened the
way for radiogenic isotope analyses, still, only diamonds with high total trace element
abundances could be analyzed.
Following the off-line concept, I developed an ablation technique of diamonds-in-water using a
‘powerful laser’ to significantly improve the amount of ablated material. The first generation used
a Spectra-Physics GCR-150-30 Q-switched Nd:YAG laser that allowed a high but variable
diamond ablation rate (between 3 and 14 mg h -1 ). However as the stage speed and incremental
movement were controlled manually during operation, the ablation pit morphology and spatial
depth were irregular and varied between ablations. The second generation off-line ablation system
in the diamond processing lab at the Hebrew University is a custom-made setup equipped with a
Spectra-Physics Talon 532-20 Nd:YV04 laser. The system is fully automated with a working area
of 20 mm × 20 mm × 20 mm, resolution of 0.5 µm, repeatability <±2 µm and a maximum speed
of 5 mm s -1 . Based on multiple ablation runs the new system's average ablation rate is 0.6 ±0.2 mg
h -1 , and we have managed to ablate up to 30 mg of a diamond.
The combination of a powerful laser and ablation in water has two major advantages. First, the
amount of diamond that can be ablated using such a laser in a timely manner is several mg.
Second, because the ablated area is underwater, the trapping efficiency is very high and allows
efficient retrieval of the nanosized analyte particles. In addition, all the material trapped in the
microinclusions is ablated and digested by acids, so possible elemental and isotopic fractionation
induced by ablation are avoided. Using the system and analyzing the ablated material by state-of-
the-art mass spectrometers we now get accurate trace-element analyses and Sr, Nd and Pb
isotopic data on individual microinclusion-bearing diamonds.