['the', 'original', 'concentration', 'to', 'allow', 'weak', 'secondary', 'absorption', 'features', 'to', 'be', 'detected.', 'A', 'spliced', 'spectrum', 'would', 'be', 'used', 'in', 'the', 'data', 'reduction', 'A', 'second', 'approach', 'to', 'achieving', 'improved', 'background', 'suppression', 'could', 'be', 'implemented', 'if', 'it', 'were', 'possible', 'to', 'selectively', 'modulate', 'the', 'hydrazine', 'concentration.', 'This', 'requires', 'a', 'method', 'of', 'chemically', 'stripping', 'hydrazine', 'from', 'the', 'smoke', 'without', 'affecting', 'the', 'other', 'smoke', 'components', 'that', 'absorb', 'in', 'the', 'hydrazine', 'spectral', 'regions.', 'If', 'this', 'were', 'possible', 'it', 'would', 'eliminate', 'the', 'need', 'to', 'subtract', 'off', 'components', 'individually.', 'Instead', 'smoke', '—', '(smoke-hydrazine)', 'would', 'give', 'a', 'hydrazine', 'spectrum.', 'We', 'have', 'used', 'this', 'type', 'of', 'sampling', 'scheme', 'to', 'detect', 'atmospheric', 'levels', 'of', 'nitric', 'acid', 'and', 'the', 'hydroperoxyl', 'radical', 'in', 'the', 'laboratory.', 'It', 'will', 'be', 'a', 'challenge', 'to', 'find', 'an', 'appropriate', 'modulation', 'scheme', 'for', 'hydrazine.', 'However,', 'the', 'high', 'reactivity', 'of', 'hydrazine', 'increases', 'the', 'potential', 'of', 'finding', 'an', 'appropriate', 'scheme.', '14', 'Lboz6eEecs0r']