{'fraction_non_alphanumeric': 0.011861313868613138, 'fraction_numerical': 0.0018248175182481751, 'mean_word_length': 4.994535519125683, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Time-gated resonance schlieren studies of analyte distribution in a graphite furnace atomiser

A time-gated resonance schlieren system has been used to observe the distribution of analyte in the furnace during the course of atomisation in graphite furnace atomic absorption spectrometry. The system is a simple one lens schlieren configuration using a pulsed dye laser tunable near the resonance wavelength of the analyte as its source and a modified 35-mm camera for image recording. It is capable of producing a series of schlieren photographs from a single firing of the atomiser. Experimental results for the atomisation of sodium suggest the existence of sodium atom concentration gradients within the furnace. For a time during atomisation, sodium atom density is lower near the furnace wall than in the centre of the furnace. It is postulated that the observed gradients are due to a strong interaction of the atomic sodium with the graphite. The gradient arises as atomic sodium, generated within the furnace through a gas phase dissociation mechanism, is adsorbed on to the furnace wall.